An iPad with only 32GB of internal storage is very space constrained. Internal storage contains the iOS/iPadOS System Software (~10GB) plus user storage to save files and photos. You must also allow additional “working space” for the iPad to store and process temporary files.
For normal operation, you will need to have at least 4-6GB of available free space - as otherwise your iPad will struggle to operate. You cannot completely fill your internal storage with your saved files and photos.
As described, you have considerably less free space than you iPad needs to operate - and it is for this reason that you are encountering difficulties.
It is impossible to increase the amount of RAM or internal storage in your iPad - as this is fixed during manufacture; what you have is fixed for the life of your device. You can, however, subscribe to a higher tier of iCloud storage - but this is not a substitute for internal storage.
Upgrade to iCloud+ - Apple Support
If your internal storage is full, your only option is to better manage the storage that you have - and delete unused Apps or unneeded data.
These support pages may 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. As your iPad has a Lightning port, you would need an Apple Lightning to USB3 Camera Adapter:
- Lightning to USB 3 Camera Adapter
https://store.apple.com/uk/xc/product/MK0W2ZM/A