iPad storage is full and limited to 64 GB

You may struggle with an iPad that has so little internal storage. The 32/64GB devices are generally intended for use in Educational settings, or in environments where the ability to store local data on the device is not required.

It is generally recommended that you always maintain at least 4-6GB of free space at all times - as your iPad needs some temporary space to complete many tasks. When performing system software updates, you may temporarily require more...

A system software update requires sufficient space to be downloaded, unpacked and verified prior to installation - major version updates requiring considerably more space than an incremental point-update. The required space, to perform an OTA update, is typically double the stated space for the installed update; after the update is successfully completed, temporary files are automatically deleted - returning free space.

If your internal storage is full, or is insufficient for the task that you need to perform, your only option is to better manage the storage that you have - and delete unused Apps or unneeded data. 

These support pages should prove to be helpful:

About storage on your device and in iCloud – Apple Support

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

Manage your iCloud storage – Apple Support

How to check the storage on your iPhone, iPad and iPod touch – Apple Support

Clear Other storage on your iPhone or iPad - Apple Support

“Offloading” Apps can be a helpful method of creating temporary space for a software update:

https://9to5mac.com/2020/01/21/how-to-offload-apps-in-ios-to-save-space-without-deleting-their-data/

Additional information about creating sufficient space for installation of a software update can be found here:

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

External storage options can often help with managing limited internal storage. Depending upon your iPad model, the iPad will either have a Lightning or USB-C port - and may therefore require either an Adapter or USB hub to connect the USB Storage device. If your iPad has a Lightning port, you’ll need an Apple Lightning to USB3 Camera Adapter:

• Lightning to USB 3 Camera Adapter

https://store.apple.com/xc/product/MK0W2ZM/A

Using a Mac computer or Windows PC can help with system software updates - as the update package is initially downloaded to the computer, unpacked and verified by the computer, prior to the computer installing the updated system software on the target device.

If short of available storage and need to perform a system software iodate, a workable remedy is to ensure that you have either an iCloud or iTunes backup of your iPad - and then completely erase the iPad. With no user-data present, you should be able to update the iPad; once updated, you can restore your backup to the iPad.

How to back up your iPhone, iPad, and iPod touch - Apple Support

Erase all content and settings:

Settings > General > Transfer or Reset iPad > Erase All Content & Settings

After the reset, set-up the iPad with your AppleID - but do not restore the backup. Perform the system software update using whichever method works for you.

Finally, restore the backup to your iPad:

Restore all content to iPad from a backup - Apple Support

To "survive" with 64GB of storage and if you haven't already done so, follow these tips.

1. Go to Settings > General > iPad Storage and turn on the "Offload Unused Apps" feature. This uninstalls the app to free up storage while keeping your saved data. If you need it again, just redownload it and pick up right where you left off.
2. Rely on iCloud, Google Drive, or OneDrive to store heavy photos, videos, and documents. Turn off full-resolution photo downloads on your device by selecting the "Optimize iPad Storage" option in your Photos settings.
3. Check apps like Netflix, Spotify, Prime Video, or Disney+. They often accumulate gigabytes of movies or playlists automatically downloaded for offline use that you may have already watched.
4. Apps like TikTok, Instagram, and Telegram devour storage by accumulating temporary data. Since iPadOS doesn't have a "clear cache" button for many of these apps, the quickest fix is often to uninstall and reinstall them.

The device was manufactured with 64 GB capacity. This is not possible to alter after manufacture. If you need more space you will need to delete or remove existing content.

Since your tag line says that you are running iPadOS 26, I'm guessing that you have an iPad (8th generation) or later. The 8th generation ones had 32 or 128 GB of storage, so it doesn't sound like you have one of those.

The 9th and 10th generation iPads were available with either 64 or 256 GB of storage. 64 GB is a fairly minimal amount. While the 64 GB models were cheaper than the 256 GB ones, the 256 GB ones probably represented better value.

The iPad (A16) is available with 128 GB, 256 GB, or 512 GB of storage – and if you plan to run a lot of games, or store a lot of music / TV shows / movies on an iPad, even 128 GB could get cramped sooner than you think.