It’s YOUR handwriting, whether cursive or printed handwriting, if you have bad handwriting, then there is no niotes app that is going to help with that, other than you constantly practicing your own handwriting more regularly on your iPad to get better writing more neatly and legibly.
Most of the paid notes app have smart zoom where you can write normally in a magnified, zommed in area that can make your handwriting, at least look more uniform .
You also, have the option in Notability to add/toggle on/off a paper grid in subdued colors to help to give your handwriting a much straighter look.
You simply need to practice to get better handwriting OR simply go back to typing out all your notes OR using Notability's audio recording feature to record a lecture or presentation, then hand transcribe or type the audio later and delete the audio.
My hand printing is much better than my cursive writing as I worked in engineering and did s lot of hand drawing/draughting/and hand lettering for many, many years!
So, my hand printing of letterforms is much neater than my cursive writing, which has gone by the wayside, somewhat, over the years.
Search YouTube for videos to help you with handwriting in Notability and other major third party notes apps for iPad/iPadOS.
There are plenty of videos that should help you with your handwriting difficulties/issues.
Best of Luck to You!