Must I go to an Apple store and buy a additional Icloud Plan?
must I buy an additional Icloud Plan to activate my Icloud?
No. An Apple ID offers 5 GB. That’s good enouh for various users and uses. For iPhone or iPad backups, more storage is usually needed, either more storage in iCloud or storage on a local Mac or Windows system.
Additional iCloud storage can be acquired online.
Click or tap for more info > Upgrade your iCloud storage plan - Apple Support
And how to > Manage your iCloud storage - Apple Support
And the Apple One subscription packages might interest > Bundle Apple subscriptions with Apple One - Apple Support
Details on iCloud storage can vary by country and region > iCloud storage plans and pricing - Apple Support