Need help on how to transfer data from my old mini iPad to my new iPad Pro already have sign in can’t fin transfer mode

How old is this old iPad?

To use the Quick Start feature of your new iPad you will need to go into the Settings app, General settings and use the Reset panel to Erase all contents and settings and setup your new iPad from the beginning, again.

Again, I ask, how old is this old iPad you are trying to transfer data from?

If your old iPad is too old and the iOS version is too old, you will NOT be able to use the Quick Start feature.

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