Why is iCloud still full after I bought more storage?

Which "full" message am I seeing?

Read the wording closely. iPhone Storage Full or "Storage Almost Full" refers to the phone. iCloud Storage Is Full refers to the cloud. A 2 TB plan, at $9.99 a month in the US or £8.99 in the UK, does nothing for the first message.

To fix phone storage, go to Settings > General > iPhone Storage and act on the suggestions there, such as offloading unused apps or turning on Optimize iPhone Storage now that iCloud has room for originals.

What if it really is iCloud that still shows full?

1. Confirm the plan in Settings > your name > iCloud. If it still shows 5 GB, the purchase landed on another Apple Account; check the receipt email.
2. If you share the plan through Family Sharing, open the usage bar and see whose data fills it.
3. Give it time on Wi-Fi. A backup or upload that failed while full may need you to start it again under iCloud Backup > Back Up Now.
4. Restart the phone, then check the bar again.

Family Sharing is the quiet one. When you share a plan, everyone draws from the same pool. A teenager backing up two devices and a long video library can fill 200 GB without you adding anything. The usage bar breaks the pool down by person, so you can see who to talk to.

Also look at the size you bought. Moving from 50 GB to 200 GB looks generous, but if your library plus backups is already 230 GB, you are still over. The bar shows your total; compare it to the plan before assuming the upgrade failed.

How do I stop it filling up again?

A bigger plan buys time, not a fix. Duplicates, burst repeats and old backups keep growing, and every new phone adds another backup to the pile. Set a reminder to review usage every few months, when the gap is still small. Clearing them now can let you return to a smaller tier later; the iCloud guide lists the order, and what to delete first is the quick version.