How can I update the software ofmy IPad?

Update your iPhone, iPad, or iPod touch - Apple Support

If you own a 7, 8 or 9-year old iPad, you won't.

Your iPad is too old, now.

If you need/want an iPad with the most current OS with current, updated apps, then you to seriously consider a new iPad model OR a “newer” , used iPad model capable of running the latest iPadOS versions.

There are plenty of newer, older iPad models that can run the most current versions of iPadOS 14.

Sorry & Best of Luck to You!