iCloud 50 gb

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

If you have an iCloud subscription, you will receive a monthly bill from Apple, check your email box.

See -> How to use iCloud on iPhone -> Use iCloud on iPhone – Apple Support (UK)

It is not clearly, what exactly do you mean by 5 GB?

See -> What's the difference between device storage and iCloud storage?

What's the difference between device storage and iCloud storage? - Apple Support

You need to turn iCloud features On or Off, see -> Use iCloud on iPhone

Use iCloud on iPhone – Apple Support (UK)

•  iCloud provides you with an email account and 5 GB of free storage for your data.

For more storage and additional features, see -> Upgrade to iCloud+ -> Upgrade to iCloud+ - Apple Support

See also: iCloud+ plans and pricing -> iCloud+ plans and pricing - Apple Support

Check also -> Manage your iCloud storage

Manage your iCloud storage - Apple Support