Now, there's a set of legitimate questions.
1. If I were Biden what would I do with regard to Covid? First, I'd authorize Booster shot vaccines for anyone who wants them, and I'd make them sign waivers acknowledging any risks. Second, I'd come out and say that I am not for a mask mandate, and then provide some details why I'm not. Being for a mask-mandate sends the wrong message about the vaccines. The vaccines fare far far more effective than masks. But, as I'm for states rights, I'd leave the mask question up to each Governor. Third, I'd make sure that theraputics like: Remdesivir, Favipiravir, Mrimepodib, Hydroxychloroquine and chloroquine, Dexamethasone (cortical steroid) and Baricitinib were widely available and easily accessible for people who even suspect they have contracted Covid (except for Dex which can be addictive among other things) . Then, I'd highlight the efficacy and potential risks about each of these treatments. Yes, I expect the President to be able to do this, not some bureaucratic "expert".
2. What can Biden do to prevent state/county governments from enacting mask mandates? If I were Biden, I'd go to each of the governors and discuss why I am against mask mandates. I would ask that they govern their state as they see best for their citizens and if that includes mask mandates, I wouldn't try and stop them. But as to the ones who are receptive to my message, I'd go a bit further. I'd remind Governors that Counties are in fact part of their State Government, and therefore under their control. I'd also remind them that they can generally preempt what city Mayors attempt to enact. See, without the ability to use police to enforce mask mandates, or by making it impossible for Cities/Counties to actually prosecute or fine "violators", the Governor's orders control. Yes, they actually do have that much power, if they aren't pussies about using it.