Can I update an IPad that is a iOS 10.3 version to an IOS 14.4?

Click on this link to read how to "Update your iPhone, iPad, or iPod touch" --> https://support.apple.com/HT204204 - When you try to update you will only be given one update selection which will be the highest available iOS version supported by your device. If it says the device is up to date and you need a higher OS version you will have to buy newer equipment.

As you are seeing, others are just essentially echoing what I told you, several hours earlier. Your "newer equipment" can be used equipment if it meets your requirements. If you buy used you must make sure somebody has gone through all the steps for selling a used iOS device or else you may end up with a device that is useless to you.

No.

Your iPad is too old for any upgrades/updates.

Sorry.

If you need/want an iPad with an up to date iPadOS with access to current, updated apps, then you really need to seriously consider a new iPad model OR a much, MUCH “newer” and less expensive, used iPad models, from better known, trusted Apple product/device retailers/resellers, capable of running the latest iPadOS versions.

There are plenty of newer, older iPad models that can run the latest, current versions of iPadOS.

Sorry & Best of Luck to You!