updating ipad software

This should explain it - Update your iPhone, iPad or iPod touch – Apple Support

If there is no update available then it means your iPad is up to date, if you tell his which iPad you have we can confirm what update you can do on it

Your first generation iPad Air can be updated to iOS 12.4.7. However, as your iPad is so far behind, as you may have already realised, you must use either a PC or Mac to update to the most recent version of iOS supported by your device.

Update software on iOS and iPadOS devices in iTunes on PC - Apple Support

If any Apps that you require now require iPadOS13 or later, replacement of the iPad with a current model will be necessary.

Yes - you can use either a PC (with iTunes installed) or Mac computer (with iTunes or Finder - as appropriate for the installed version of macOS).