Nothing at all.
This will never be possible.
If your iPad has been stuck on iOS 10.3.3 for the past few years, with no major upgrades/updates forthcoming, then you own a 2012, iPad 4th generation.
A 4th gen iPad cannot be upgraded beyond iOS 10.3.3/10.3.4 for WiFi & cellular data models.
A 4th gen iPad is a NEARLY 8-year old device, now!
These older iPad models are too old, now, too underpowered and completely incompatible with any of the current and future versions of iOS/iPadOS.
Sorry, but it is what it is, today, in the year 2020!
These old 8 and 9-year old iPad models will be rendered completely OBSOLETE by the end of 2020!
Here's why and what you will need to do about it in 2020!
Tap and read my link below for my additional info about your old iPad model.
If you own OLD 8 and 9 Year Old iPad mo… - Apple Community
Sorry & Best of Luck to You!