photoshop for 11-inch iPad Pro

The Photoshop version you can install from the App Store is not the same as the one for a computer no.

It's a full featured version for iPad, but still has differences from the computer version.

It is not pre-installed, you must download it from the App Store: link-> https://apps.apple.com/us/app/adobe-photoshop/id1457771281

You'll need an Adobe ID with a paid subscription to Adobe CC to access all the features of Photoshop.

https://www.adobe.com/products/photoshop/ipad.html

You can't. You can only purchase what Adobe offers. If the offering for iPad doesn't meet your needs, you can wait and hope Adobe one day releases those features (they have promised complete feature parity, but gave no timeline on full implementation), or you can buy a device that can run a version with the features you need (such as a macOS device).

You cannot buy the Photoshop version for iPad. You can download it for free from the App Store directly on the iPad, but you need to be subscribe to Adobe's Creative Cloud service to get access to the full Photoshop features.

When you download the Photoshop App, it will prompt you to subscribe to one of the plans.