Our office often levels codes GAC visits as lvl 4, but as everyone else mentioned, it's a little different for each patient and you need to be able to support it.
Usually our providers are prescribing medication (or adjusting the dosage), as well as ordering screening labs to verify that the patient is tolerating the prescribed hormones. If the provider orders 3 or more screening labs and does medication management, that would meet the requirements for a lvl 4 visit, regardless of how you classify the diagnosis of Gender Dysphoria in the problem level.
If the provider is not ordering labs, they may not meet the requirements for lvl 4, in which case we do code it as a lvl 3. Our office considers Gender Dysphoria as "stable chronic illness" (though we hate the language). If a patient is experiencing suicidal ideations, or preforming high risk behaviors because of their gender dysphoria, or any of the things that Lady T mentioned above, I have asked providers specifically notate those so that I can add them as additional diagnoses, and support the higher level office visits that way.
Hope that helps a bit more as well. Thank you for providing GAC!
-KM