The L.A Chargers can they beat the Chiefs or the Rams?

It depends on well they can play against either team.

Rams no, Chiefs yes.

They're a good team so they could but they wouldn't be favored right now going into the game.

Yes they could on a good day

Once they are rolling, they can if they have home field. None of the top 3 teams (Saints, Rams, Chiefs, in no particular order) are losing at home.

Depends on their performance against either team.