The App Store app cannot be deleted, unless you are in Europe and it was removed after installing a different App Store.
You can look for it in the App Library and drag it back to home screen if its there.
click here ➜ Find and use your apps in App Library on iPad - Apple Support
If its not there, make sure its not restricted in Settings ➜ Screen Time ➜ Content & Privacy Restrictions ➜ iTunes & App Store Purchases ➜ Installing Apps and make sure it's set to Allow.
If you are in Europe and you installed a different App Store app, see the following support document to re-enable Apple's App Store app.
click here ➜ Delete certain built-in apps from your iPhone or iPad in certain countries or regions - Apple Support