Connect multible multible switches to same flow

can I add multible switches to same flow. I want to make sure all my light switches have same function and avoid to create 1 flow per switch.

Yes, you can add whatever devices you like in the flow. You can also set delays if you like to have one device go on/off a bit later then others.

In the Then part as an action, yes.

In the if Part as a trigger, no

you can use the Group app to gather the switches.