2 - 3 tries on an FC turbo starter will trip a 100A no problem.
Each try averaging about 5 - 10 seconds.
I would recommend a minimum of 150A on the circuit breakers, unless you like tripping and resetting them all the time.
It could be used as a security feature?

A good, working starter should fire the engine on the first try.
I run a pair of old-school 200A circuit breakers and have had zero problems of them tripping with the starter.
You can find 150A units pretty easily, but I can't find higher rated ones like these anymore these days.
-Ted