The problem with iPads these days isn't the size, it's the extremely poor battery life compared to the iPhone . Both my 11 and 12,9 inch iPads don't last over ~4-5 hours when I use it continuously and they're just the 2021 and 22 models. My iPhone 13 PM last twice longer than both my iPad and it's not normal. Because of that I simply use my phone more instead of using both my iPads that are now used almost exclusively to watch content on it.
The performance is already powerful enough as well. If they don't update the battery at all, I simply don"t care anymore. I don't think the new oled screen will be much different than the already amazing miniLED screen of the 12,9 one.