Start with your law in that location
Someone will have put out emergency orders or other directives indicating exactly what must be done. For instance in the USA these are issued at the state level, and further instructions are ordered at the county or municipality level. Know them all. Some of them are amended quite frequently.
A few are mandatory with zero penalty. Still do those. That's a bit of legal chicanery to create civil liability for the scofflaw.
The reasons are: first, you need to comply with the law. The effect on the employer is that they will see that you are reasonably informed about the crisis, and are not a scofflaw or a sociopath, and do not recklessly put others into harm's way. We'll loop back on that.
This tells you about them, too.
And second, you need to be able to evaluate whether the company is complying with the law, so that you can evaluate them and determine whether this will be a workplace that is safe, comfortable, and conforms to your values and risk-taking levels.
Further, this allows you to evaluate whether the company "walks their talk" regarding social action, safety, whatever the case may be.
So you're looking for signs and reactions. Do you see masks on, do you see nods of approval, do you see people scoff or roll their eyes, do you see masks off until you roll up, then the masks snap on. It's not even really about legal compliance, and it's certainly not about politics... though it is about whether they let politics get in the way of safety.
Every company has a safety culture - we had one on here a few years ago who wanted sysadmins to move 2000-pound computer racks using dollies on a 10% grade... Then you have Kiewit, which overhauled half of one of the biggest dams in the country, 600 workers onsite working off cliffs, canyons and a 25% grade... no reportable injuries for over a year, and finished the project with 2. You're gonna want your mask for that interview.
The science behind the laws.
Editing for brevity: 2 common assumptions are wrong.
"I'm only contagious after I feel sick" -COVID-19 is so insidious because you become contagious for q long period before you feel sick. Some are contagious but never feel sick (beyond their normal for stress/allergies).
"My mask protects me, your mask protects you" - the science shows that any masks are highly effective at keeping a sick wearer from exhaling virus particles, and not very effective at protecting a healthy wearer. Even medical-grade masks require a full suite of PPE to reliably protect the wearer.
Together these add up to: masks work if everyone does them, since we can't know if they're contagious or not.