diff --git a/python/core/auto_generated/expression/qgsexpressioncontextutils.sip.in b/python/core/auto_generated/expression/qgsexpressioncontextutils.sip.in
index 0b652f7248c..fa0c2e58f8a 100644
--- a/python/core/auto_generated/expression/qgsexpressioncontextutils.sip.in
+++ b/python/core/auto_generated/expression/qgsexpressioncontextutils.sip.in
@@ -240,7 +240,7 @@ with the variables specified.
 .. versionadded:: 3.0
 %End
 
-    static QgsExpressionContextScope *atlasScope( QgsLayoutAtlas *atlas ) /Factory/;
+    static QgsExpressionContextScope *atlasScope( const QgsLayoutAtlas *atlas ) /Factory/;
 %Docstring
 Creates a new scope which contains variables and functions relating to a :py:class:`QgsLayoutAtlas`.
 For instance, current page name and number.
diff --git a/python/core/auto_generated/layout/qgsabstractlayoutiterator.sip.in b/python/core/auto_generated/layout/qgsabstractlayoutiterator.sip.in
index 2ba868c4e43..98119ecddd4 100644
--- a/python/core/auto_generated/layout/qgsabstractlayoutiterator.sip.in
+++ b/python/core/auto_generated/layout/qgsabstractlayoutiterator.sip.in
@@ -41,7 +41,7 @@ is available or required.
 Ends the render, performing any required cleanup tasks.
 %End
 
-    virtual int count() = 0;
+    virtual int count() const = 0;
 %Docstring
 Returns the number of features to iterate over.
 %End
diff --git a/python/core/auto_generated/layout/qgsabstractreportsection.sip.in b/python/core/auto_generated/layout/qgsabstractreportsection.sip.in
index 275621839b1..e2434a9dcf3 100644
--- a/python/core/auto_generated/layout/qgsabstractreportsection.sip.in
+++ b/python/core/auto_generated/layout/qgsabstractreportsection.sip.in
@@ -105,7 +105,7 @@ Returns the parent report section.
 Returns the associated project.
 %End
 
-    virtual int count();
+    virtual int count() const;
 
     virtual QString filePath( const QString &baseFilePath, const QString &extension );
 
diff --git a/python/core/auto_generated/layout/qgslayoutatlas.sip.in b/python/core/auto_generated/layout/qgslayoutatlas.sip.in
index 5f4d357dcc4..727dba479a7 100644
--- a/python/core/auto_generated/layout/qgslayoutatlas.sip.in
+++ b/python/core/auto_generated/layout/qgslayoutatlas.sip.in
@@ -267,7 +267,7 @@ number of matching features.
 
     virtual bool endRender();
 
-    virtual int count();
+    virtual int count() const;
 
     virtual QString filePath( const QString &baseFilePath, const QString &extension );
 
diff --git a/src/core/expression/qgsexpressioncontextutils.cpp b/src/core/expression/qgsexpressioncontextutils.cpp
index 37be7e786b9..ae55c6e5932 100644
--- a/src/core/expression/qgsexpressioncontextutils.cpp
+++ b/src/core/expression/qgsexpressioncontextutils.cpp
@@ -514,7 +514,7 @@ void QgsExpressionContextUtils::setLayoutVariables( QgsLayout *layout, const QVa
   layout->setCustomProperty( QStringLiteral( "variableValues" ), variableValues );
 }
 
-QgsExpressionContextScope *QgsExpressionContextUtils::atlasScope( QgsLayoutAtlas *atlas )
+QgsExpressionContextScope *QgsExpressionContextUtils::atlasScope( const QgsLayoutAtlas *atlas )
 {
   QgsExpressionContextScope *scope = new QgsExpressionContextScope( QObject::tr( "Atlas" ) );
   if ( !atlas )
diff --git a/src/core/expression/qgsexpressioncontextutils.h b/src/core/expression/qgsexpressioncontextutils.h
index e22dc9672e9..13cb706d8fb 100644
--- a/src/core/expression/qgsexpressioncontextutils.h
+++ b/src/core/expression/qgsexpressioncontextutils.h
@@ -222,7 +222,7 @@ class CORE_EXPORT QgsExpressionContextUtils
      * For instance, current page name and number.
      * \param atlas source atlas. If NULLPTR, a set of default atlas variables will be added to the scope.
      */
-    static QgsExpressionContextScope *atlasScope( QgsLayoutAtlas *atlas ) SIP_FACTORY;
+    static QgsExpressionContextScope *atlasScope( const QgsLayoutAtlas *atlas ) SIP_FACTORY;
 
     /**
      * Creates a new scope which contains variables and functions relating to a QgsLayoutItem.
diff --git a/src/core/layout/qgsabstractlayoutiterator.h b/src/core/layout/qgsabstractlayoutiterator.h
index 153a84b2aee..4ca46f7e545 100644
--- a/src/core/layout/qgsabstractlayoutiterator.h
+++ b/src/core/layout/qgsabstractlayoutiterator.h
@@ -54,7 +54,7 @@ class CORE_EXPORT QgsAbstractLayoutIterator
     /**
      * Returns the number of features to iterate over.
      */
-    virtual int count() = 0;
+    virtual int count() const = 0;
 
     /**
      * Iterates to next feature, returning FALSE if no more features exist to iterate over.
diff --git a/src/core/layout/qgsabstractreportsection.h b/src/core/layout/qgsabstractreportsection.h
index c5c1e2c0da6..6c153097e87 100644
--- a/src/core/layout/qgsabstractreportsection.h
+++ b/src/core/layout/qgsabstractreportsection.h
@@ -121,7 +121,7 @@ class CORE_EXPORT QgsAbstractReportSection : public QgsAbstractLayoutIterator
     QgsProject *project();
 
     // TODO - how to handle this?
-    int count() override { return -1; }
+    int count() const override { return -1; }
 
     QString filePath( const QString &baseFilePath, const QString &extension ) override;
     QgsLayout *layout() override;
diff --git a/src/core/layout/qgslayoutatlas.cpp b/src/core/layout/qgslayoutatlas.cpp
index ee1baac2197..cacb90dfa07 100644
--- a/src/core/layout/qgslayoutatlas.cpp
+++ b/src/core/layout/qgslayoutatlas.cpp
@@ -340,7 +340,7 @@ bool QgsLayoutAtlas::endRender()
   return true;
 }
 
-int QgsLayoutAtlas::count()
+int QgsLayoutAtlas::count() const
 {
   return mFeatureIds.size();
 }
@@ -447,7 +447,7 @@ QgsExpressionContext QgsLayoutAtlas::createExpressionContext() const
     expressionContext << QgsExpressionContextUtils::projectScope( mLayout->project() )
                       << QgsExpressionContextUtils::layoutScope( mLayout );
 
-  expressionContext.appendScope( QgsExpressionContextUtils::atlasScope( const_cast< QgsLayoutAtlas * >( this ) ) );
+  expressionContext.appendScope( QgsExpressionContextUtils::atlasScope( this ) );
 
   if ( mCoverageLayer )
     expressionContext.appendScope( mCoverageLayer->createExpressionContextScope() );
diff --git a/src/core/layout/qgslayoutatlas.h b/src/core/layout/qgslayoutatlas.h
index 2807b33ba31..60f9fba8f34 100644
--- a/src/core/layout/qgslayoutatlas.h
+++ b/src/core/layout/qgslayoutatlas.h
@@ -245,7 +245,7 @@ class CORE_EXPORT QgsLayoutAtlas : public QObject, public QgsAbstractLayoutItera
 
     bool beginRender() override;
     bool endRender() override;
-    int count() override;
+    int count() const override;
     QString filePath( const QString &baseFilePath, const QString &extension ) override;
 
     /**