Are you supposed to keep your legs straight when doing squats? ?

By straight I assume you mean directly below your body, with feet very close together? There are various ways to squat which include feet together, feet shoulder width apart, a bit wider than shoulder width, and feet a lot wider (sumo squat). Each different position, works the muscles a bit differently. For instance, when your feet are together it's a bit harder to keep your balance as you squat down, so muscles are recruited to help with that (and those same muscles aren't needed as much when you squat with your feet wider apart). Here's some info on form and foot position https://www.muscleandfitness.com/workouts/leg-exer...

No, how could you go into a squatting position if you keep your legs straight?  You have to squat down and bend.  Best exercise for glutes, and quadriceps.

Can't really squat without bending your legs.  How far you set your feet apart is somewhat a matter of personal preference.

Wow... no knees bent and getting into a squat position!