He doesn't have that power, nor does Biden. They can tell you what to
do when you are on executive branch property but out in the world
perhaps a governor could but not the federal government. (10th
amendment)
===
The important thing is for the POTUS to lead by example and not mock
people who are trying to do the right thing. It's also important to
show some respect for science and medical professionals, unlike DJT.
It is hard to find anyone in DC that lives up to that lofty goal. All
of them seem to get caught on camera without their mask in places
where they should be wearing one.
I also question the science when a "mask" can be anything from a neck
gaiter to a certified KN95 respirator and we are supposed to believe
they are the same.
I doubt 10% of the people do everything right.
https://www.huffpost.com/entry/face-mask-mistakes-covid-19_l_5ff35c27c5b65a92291089df
That's the Huff Post so even Harry will have to agree.