Re: "IOS 26 on IPad. The onscreen keypad is taking up two thirds or more of the screen.
The buttons are huge, expect space bar which is only about two keys wide."
Seems you can easily switch between the full-sized keyboard and the smaller keyboard:
Apple support's online article for iPadOS 26: Type with the onscreen keyboard on iPad - Apple Support
Eg says:
"Enter text using the onscreen keyboard
In any app that allows text editing, open the onscreen keyboard by tapping a text field.
You can pinch closed to shrink the keyboard, then tap individual keys to type, or use QuickPath to type by sliding from one letter to the next without lifting your finger (not available for all languages).
To end a word, lift your finger. (If you tap
after sliding to type a word, it deletes the whole word.)
You can drag the smaller keyboard from the bottom of the screen to move it wherever you want for easy one-handed typing.
To return to the full-size keyboard, pinch open. On the full-size keyboard, you tap keys to type."
NB: There are many more keyboard tips in the above linked article.