if someone is interested into trying out, there are certain places where you can tp in and out while walking specifically into a certain direction (example fire, energy and earth portals) technically is walking so nothing should stop you from being more than 15m doing that (beside a player who move you) now, this per se, doesn't answer the question so is up to whoever willing to take the task to find a place with all the needed conditions.
There are certainly other places that let you do that without removing your target, example mountain tomb levers teleport, and there are even other places where we could "walk few steps before arriving the tp" (as oramond sewer to dp but instead of being teleported just get pushed away) but i would update their location later due atm i don't remember them.