Do you have 18' ceilings? Do a standard door with a transom.

That’s not an online purchase. That is done through the expensive lumber yard/ supply house and will be custom.

Consider rethinking the design.

If that's for the mudroom, I can only imagine the main entrance!

Google is your friend. Lots of listings for custom door cos. in your area.

I have a 10 ft high front door, custom built by a local door builder in my area. Not something you buy off the shelf!

I have found tall doors come in handy when you do not want to reel in the string on your helium balloon.