I'm sorry i'm a bit confused here but do you want to compare current user with values in a list or do you want to compare it with an input field?
If it's the latter then maybe something like
If(Office365Users.MyProfile().UserPrincipalName = TextInput1.Text, true, false)
in "visible" of the fields you want to hide/show or put it in a variable.
If it's the first one then maybe this If(!IsBlank(LookUp(List, User.Email = Office365Users.MyProfile().UserPrincipalName)), true, false)
Hope this helps
Edit : edited mistake in 2nd formula