Cannot create a new folder in my mailbox

Hi J_Reid-1945,

Thanks for coming to Apple Support Communities for help today.

Have you followed the steps found here: Use mailboxes to organize email on your iPhone or iPad? Double-check them and try once more.

"Create custom mailboxes

1. In the Mailboxes list, tap Edit in the upper-right corner, then tap New Mailbox.
2. Give your mailbox a name. If you have more than one email account set up on your device, tap Mailbox Location and choose the account where you want to create a mailbox.
3. Tap Save, then tap Done.

You can find your new mailbox in the Mailboxes list under the account where you created it."

If that isn't working, can you create one on your provider's web portal? Does it show up in your iPadOS Mail app?

Also be sure your iPad is completely updated to rule out this being related: Update iPadOS.

If this doesn't help, let us know more details.

Have a fantastic day!