To summarise your subscriptions -
Your Apple One individual plan affords you 50GB of iCloud Space.
Your iCloud+ plan is the 200GB space.
They are available concurrently and together give you 250GB
What happens to your iCloud storage when you sign up for Apple One advises the following:
If the iCloud storage included in Apple One is less than your current plan
You will keep both your current iCloud+ plan and the iCloud storage in Apple One.
This is the current setting - you have kept the larger and existing 200GB iCloud+ plan to which the Apple One 50GB has been added.
Were you to upgrade to the Family Apple One plan you would terminate your existing 200GB iCloud+ plan:
If the iCloud storage included in Apple One is equal to your current plan
During the free trial, you will keep both your current iCloud+ plan and the iCloud storage in Apple One. Once the trial has finished, your current iCloud+ plan will be cancelled. Your total iCloud storage will be the amount included in your Apple One subscription.
*Ignore for the moment the quoted text about free trials - this is for those who have not already subscribed to Apple One.
If you are concerned about space on iCloud, especially as you seem to be adding a Family Sharing group, consider the Premier plan which gives you the top tier of iCloud space - 2TB - for a small additional fee per month.