Hi @cat206 ,
Are you hoping to create an attribute expression for a pop-up that shows the last time a record was edited?
This is possible by first creating a field that provides the last date and time that a record was edited as well as the user who edited it. To do so, enable editing and track changes in the Settings page of that feature layer (See screenshot below).
Once these settings are enabled, you can turn on this field from the Data tab of the feature layer (See screenshot below).