There is no way to record to a DVD from ANY IPad.
First, you need CD/DVD burning software and there is no such software for iOS.
And you need a software DVD/Blu-ray player to test the final burned disc.
There are no external hard drives or optical media drives that will work with iPads as the power draw is too great for the IPad Pro’s less powerful power supply.
You will need to find a way to transfer this video to a computer with a built-in or externally connected optical drive and you need to use optical disc burning software to burn the edited video to the proper disc format to play in a DVD or Blu-ray disc player.
You would need to transfer this file either using iTunes on a computer or through iCloud OR though a cloud, offsite data storage service app, like DropBox, Google Drive, etc. to transfer your edited movie to an actual computer to create a video DVD/Blu-ray disc
There is simply NO way to this from an IPad.
There is none of this capability in iOS.
Sorry.