I have a 10.5 iPad Pro which still performs well. I don't need to upgrade for performance.
I read quite a lot on the iPad and I wonder if the experience will be (even) better with the new iPad Pro 11.
You would get a slightly bigger screen. If you can afford it - why not. You can also enjoy the ’quality of life’ upgrades of CPU, RAM, camera, Thunderbolt, Face ID etc as well.
There's nothing 'wrong' with the 10.5 🙂 Reading on the iPad for longer periods of time is not that comfortable on my eyes and I wonder if the 2021 screen is any different and maybe worth the upgrade in that regard.