Expanding upon Lobsterghost1’s comments…
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, this being a finite resource:
What's the difference between device storage and iCloud storage? - Apple Support
You appear to have a base-model, with only 16GB internal storage, of which the Operating System (iOS) will consume a considerable proportion of your available device storage. With a space-constrained device, such as yours, you are always likely to struggle with available storage on your iPad.
If your internal storage is full, as illustrated in your screenshot, your only option is to better manage the storage that you have - and delete unused Apps or unneeded data.Â
These support pages should prove to be helpful:
About storage on your device and in iCloud – 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