It’s showing me 200GB only I don’t want it I need 50GB

Check which iCloud subscription you do have now -> Go to -> Settings -> your name -> iCloud -> if you see 50 GB (or 200 GB or 2 TB) then you have an iCloud subscription.

See this Apple article: Downgrade or cancel your iCloud+ plan

Downgrade or cancel your iCloud+ plan - Apple Support (PH)