I understand this could be possible with custom widgets in the Developer Edition of ExB, with some coding:
Alternatively, please feel free to post this in ArcGIS Experience Builder Ideas as well:
If this answer solved your question, please mark it as "Accept as Solution" to help others who have the same question.
In the LayerList , in
I know this is an older post but this is a feature I could use. It didn't look like anyone added this to the ArcGIS Ideas website so I went ahead and created one. https://community.esri.com/t5/arcgis-experience-builder-ideas/expand-grouped-layers-by-default/idi-p....