Well, the iPad 10 does have a few advantages over the iPad 9:
USB-C vs Lightning connector
Landscape two speaker audio vs two speakers
10.9 inch vs 10.2 inch display
Landscape front facing camera
A14 vs A13 chip, 16-core vs 8-core neural engine
4GB vs 3GB RAM
12MP vs 8MP rear camera
4K video recording
Greater color selection and updated form factor
I am probably forgetting some things.
Anyway, the retail price difference is about $120. Only you can decide if these things are worth it for your particular needs. In my case, I got my iPad 10 on sale for $419 and plan to keep it for about 4 years. That seemed like a reasonable deal to me, but YMMV.