You can use Contains() for that. It will feel a little backwards when you’re really trying to produce an IN clause, but this should do it:
var userProfiles = _dataContext.UserProfile
.Where(t => idList.Contains(t.Id));
I’m also assuming that each UserProfile record is going to have an int Id field. If that’s not the case you’ll have to adjust accordingly.
https://stackoverflow.com/questions/16824510/select-multiple-records-based-on-list-of-ids-with-linq