Can I use Quick Start to transfer from a 5th gen iPad to a 10th gen iPad?

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

Punster46 wrote:

Can I use quick start to transfer from a 5th generation iPad to a 10th generation iPad?

Both ipad needs to be on ios 11 or higher to use quick start Use Quick Start to transfer data to a new iPhone or iPad - Apple Support

Punster46 wrote:

So you just place them next to each other and quick start is automatically activated?

pardon me for being so dense

It's outlined in that link assuming both ipad meets the requirements to use quick start.

Punster46 wrote:

Where do I find QuickStart?

Click on the blue link I provided in my original reply.