How to upgrade iOS in my iPad

Apps may require an iOS version your iPad cannot run or is not currently running.

If going to Settings->General->Software Update does not produce an available update, then your iPad is likely at the end of the road for Software Updates, and you would need a newer one that can run a newer iPadOS version to run the Apps that require said version.

See here for how to updater your iPad: link-> Update your iPhone, iPad, or iPod touch - Apple Support

Older iPads cannot be updated. The iPad 4th generation, for example, cannot be updated beyond iOS 10.3.3 or 10.3.5.