Does AMR work for 50 level characters/old BfA content in premium version?

I have recently come back to WoW after 3 years of break. I’m currently doing old BfA content at 50 level and I don’t Intend to go to Shadowlands just yet. If I go premium, will AMR show me gear upgrades from BfA dungeons/content and generally allow for the same level of optimization as for current content?

No, the website mainly offers gear advice for max level content. We only loosely support lower level characters.