Shimano Adjustable Crank Arm Length
There are sizing cranks that are primarily used by fitters. They're expensive and heavy and usually intended for a fit machine more than going on an existing bike. Ones I'm familiar with are square taper so getting them on to modern bikes would involve jumping through some hoops, but there may be a 24mm one out there.
Trying all the lengths in a short amount of time and with minimal contrivance would be a good thing to find a fitter's help with. Crank length and saddle fore-aft are numbers that play off each other, so you want to get your fore-aft dialed at the same time if you can.