The ONLY Web browser that can use add-on extensions is the iOS version of Safari.
Safari extension can be found in the iOS App Store . Some are free. Some you have to pay for.
There are NO Web browser extensions for any other third party Web browsers for iOS.
Sorry.
iPadOS has multitasking panels.
In most cases you can open two or three apps at one time and can open multiple instances of the same app to open different items within the same app.
Currently, NO iPad is NOT a replacement for a full feature laptop or desktop computer.
To learn how to use your iPad, you can download the iPad Users Guide here which downloads into your Apple Books app found on your iPad.
Tap the Apple Books link below.
https://books.apple.com/us/book/ipad-user-guide/id1567104892
Best of Luck to You!