The age old debate of “Where should my feet be when I squat/bridge/deadlift”.
The bottom line reality of this question is that there is no right or wrong answer.
There is not any one position or exercise that is 100% correct or inherently dangerous unless your body is not conditioned to handle the load.
Every body is different and how you feel in certain positions can vary greatly depending on your anatomical structure, your muscular function and what you have been exposed to prior. These components can also vary depending on which musculature you are trying to target with the specific exercise.
For each of these exercises, start with your feet somewhere between hip and shoulder width apart, toes externally rotated anywhere from 20-45 degrees and see how it feels. If you are trying to target more posterior chain (glutes/hamstrings) a wider stance will generally help facilitate this. The closer your feet are the more quad activation you will get.
Keep in mind these are GUIDELINES- you can go wider than shoulder width, you can come closer than hip width, your feet can turn in and your feet can turn out. Go through each of these movements at multiple different foot positions and see what muscles activate with which position to achieve your desired outcome.