If your iPad has been stuck on iOS 10.3.3 for the past few years, with no upgrades/updates forthcoming, then you own an iPad 4th generation.
A 4th gen iPad cannot be upgraded beyond iOS 10.3.3/10.3.4.
A 4th gen iPad is an over 7-year old device, now!
Its internal hardware is too old, underpowered and completely incompatible with any current and future versions of iOS.
Sorry. It is what it is at this very late date.
If you need an iPad that can run the latest and greatest versions of iOS, as well as, the most current apps available, then, you will need to purchase a new iPad from Apple or a discounted, refurbished iPad from Apple’s Refurbished & Clearance section of Apple’s Website.
Best of Luck to You!