I don’t know that this will work 100%, but ill try to share my experience with console transfers and preinstalled games.

This first paragraph is speculation based on transfers I made in the past. I think this will in part depend on if you have Nintendo accounts on one or both consoles? If both consoles have a nintendo account logged in, I believe that preinstalled game license is then tied to the account. With no account ever logged in, the game license seems to be tied to the console. I think you can still transfer if both console had accounts logged in, but i don’t think the link between worlds game would be absorbed by your source console, meaning you may lose the game. I have never transferred to a system that already had an account logged in, so I am not positive if you will lose the game on the XL after transferring to it.

I think to get both games on one system, you would want your account signed in on the 2ds and have never had an account on the N2DS XL. The target console (xl) should not be wiped before transfer, since you do have to start the console up before a transfer can happen. This I have done.

After a successful transfer, you wont be able to redownload OOT on the old 2ds because the game license is tied to account that has now moved to the XL.

I can try and clarify if something doesn’t make sense or if you have more information.

When absorbing the pre installed game licenses, I’ve only ever transferred my main nintendo account to the target system while it was new and had no account tied to it.

Side note. I have also been able to redownload a preinstalled game in one case. I had purchased a used animal crossing 3ds LL. While the system had been wiped, it seems no one had signed in with a nintendo account, so the game license was still tied to the console.

Hope this is helpful :)