some ideas on new parts for flamethrowers(maybe to replace simply being a setting):
(compression chamber) increased range, decreased fire size
real life flame throwers with a longer range tend to have arching fuel, so maybe that could be implemented
(fuel pump, or some other name idk) decreased range, increased fire size
(different flamethrower nozzles) allows firing the flames in different streams, straight, arching, split stream, sprinkler, fireball cannon
(sticky additive) like the fuel types, but makes it linger on the ground(or water if your flamer has oxidizer)
and probably weirdest idea
(explosive additive) some explosives aren't really ignited by heat even to rather ridiculous degrees, and instead are set off by pressure. This is essentially just that but as an additive to your flames that make them create HE explosions when struck by kinetics