Is it possible to set scale-based visibility for groups or sub-groups of layers in QGIS 3?
Currently there is no option to set scale-based visibility for a group / subgroup.
As a workaround, you can select (highlight) the layers in the group (holding Shift key, if you are on Windows), then right-click to call a context menu "Set layer-Scale visibility".
This setting is applied to all the layers you have highlighted.
