@Firebird105x Thanks for reaching out.
You need to leverage the Filter array for your requirement. In filter array you need to compare @item()['EmailAddress'] with your UserEmailAddress variable. The From will be your UserList.
The filter array will retrieve the matching values. If you have always one matching value then you need to use body('Filter_array')[0]['UserID'] to get the userID value. In case if there are more matching value then you need to leverage the loop.
For your reference sharing the reference guide of function used in logic app.
Feel free to get back to me if you need any assistance.