As in QGIS Desktop, Lizmap can use QGIS expression .
At the project level, Lizmap will set two variables in QGIS Server:
@lizmap_user: string, the current user connected in Lizmap. It might be empty.
@lizmap_user_groups: array, the current user groups as a list. It might be empty.
It’s possible use these variables in a symbology for instance, to set a different color for a given user, or to print the current Lizmap user in a layout.
For editing, it’s possible to use expressions for constraints, default value, group visibility. Read Advanced form.