Take a look at this thread in the Predator Hunting Reference Sub-forum (topline of this forum).

Predator Hunting Reference Section: Shotgun Loads and Chokes for Coyotes

The short version is this:

Considering these out of a 12ga shotgun, not 20ga.

A lot of things can work. Some better than others. Some more affordable than others. Some more over-hyped than others.

Cheapest option: 00 buck with an improved or light modified choke. I've killed hundreds of coyotes with Winchester Super-X 00buck in the last ~20 odd years.

Best option: #4Buckshot out of a 0.680" choke. Been using the Federal #4 buck for a few years now, if I could find it regularly, I'd never shoot anything else.

The #4buck will have a little more range than the 00buck, as it has a lot more pellets for a greater pattern density.

50yrds is asking a LOT of a shotgun for coyotes. Expect rollers that get up and run.

The heavier than lead T and BB shot is great stuff, but far too expensive to be a relevant choice. Not better killing than #4buck, however, in my experience.