how do i open zip files on my Ipad 11 Pro

Zip archives are natively supported by iOS/iPadOS:

How to open ZIP files on your iPhone, iPad, or iPod touch - Apple Support

Zip (.zip ) files are fully supported in iOS/iPadOS.

When you tap on a .zip file, iOS/iPadOS should just immediately unzip the file and reveal its contents for you to be able to share and/or save to the appropriate app.