First, a caveat: Touch ID does not replace your password or passcode. The iPad passcode must be entered every few days and after a restart to re-activate Touch ID. Touch ID also does not replace the passcode on a secure note in Notes app.
In addition to the Legacy Contact mechanism mentioned in replies above, you can provide password archives or a master password list kept in a safe deposit box, kept in a labeled key-locked or passcode-locked storage box at home, in the documents including a Will kept at a lawyer’s office, or written on a sticker stuck on the bottom of your keyboard or on a slip kept underneath the iPad protective case, for a wide range of situations and possibilities and preferences.
There are also so-called deadman’s services, which will periodically check on you, and that will then send a designated email to designated people if you don’t respond to the periodic prompts. (You could do an exceedingly low-budget version of this deadman with a weekly reminder to reschedule out a timed message send, too. Or most any other deferred-send mechanism.)
If you have photos or genealogy or other such data that can be of interest to some of your friends and relatives, I would look to share copies of that data now, with those that are interested.
If you do have the money for a lawyer and a will, ask them for suggestions, too.
