This can be done in a few different ways. If you are using Concepts version 6.12 you can move all your drawings to the iCloud Drive location in the gallery. Once you move the drawings there, they are saved to your iCloud and will be available on any device logged in with the same Apple ID. To learn how to move your drawings, read this.

The other way to do this is to backup the whole iPad to iCloud and restore the other iPad from this backup. This transfers all of your content including Concepts drawings. Apple has help on this.

You can also manually backup ( export) your drawings to a cloud service ( iCloud, Google Drive, Dropbox, etc) and then import onto the new device.
1. Open the iOS Files app
2. Go to "On My iPad"
3. Create a new folder called Concepts Backup and move it to "iCloud drive" (or another cloud location)
4.  Go back to the "On My iPad" location and open the Concepts folder
5. Tap Select in the top right corner
6. Tap every folder in the Concepts folder to select it
7. Tap Copy in the bottom bar
8. Navigate to the new Concepts Backup folder you created
9. Tap and hold to bring up a menu, then tap paste

Once this is done, then you can import those drawings onto the new device via the same cloud service that you backed them up to.

You can drag the folders from the location to the "On My iPad> Concepts" location on the new iPad to import them.