@inthehands An important tool in my bystander toolbox is one I learned from someone on Twitter a few years ago: say Wow.
Someone says/does something racist/sexist/fascist/ableist/etc? Say “Wow.”
It interrupts and draws attention. It treats whatever came before as out of the ordinary. It doesn’t support the other person, but it also doesn’t immediately make them defensive. It buys you time to figure out what to say/do next