I have an iPad 4 running on ipadOS 10. How do I transfer data from it to a new iPad Pro?

These support pages should get you started with setup of your new iPad - and the methods of transferring your data from old to new iPad:

Set up your iPhone, iPad or iPod touch – Apple Support

Transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support

Use Quick Start to transfer data to a new iPhone, iPad or iPod touch – Apple Support

If the donor iPad, from which you are transferring your data precedes iOS12.4, QuickStart will not be available.

“Transfer” is rather a misnomer. In reality, your data and setup is merely cloned to the new device. Nothing is moved or removed from the original device.

An alternative is to restore either an iCloud or iTunes backup to the new device:

How to back up your iPhone, iPad and iPod touch – Apple Support

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

When you are ready, the best procedure for preparing you old device for disposal or reuse can be found here:

What to do before you sell, give away or trade in your iPhone, iPad or iPod touch – Apple Support

Select your preferred (doable) method among the ones listed in this support article:--> Transfer data from your previous iOS or iPadOS device to your new iPhone, iPad, or iPod touch - Apple Support

Regards

Giulio

You are very welcome.