No, it doesn’t, back in May of 2020 the CDC released the results of 14 individual studies conducted by various universities and medical institutions on the effectiveness of the mask in preventing the spread or preventing contracting the influenza virus, which is 220 nm's on average. The results were all the same. Neither did the mask slow down or prevent the spread of the virus nor did it prevent or slow down the infection rate of the virus.

So if the masks do nothing for the influenza virus why would it be effective against a much smaller virus (Covid)?

CDC- Volume 26, Number 5—May 2020
Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings—Personal Protective and Environmental Measures

“In our systematic review, we identified 10 RCTs that reported estimates of the effectiveness of face masks in reducing laboratory-confirmed influenza virus infections in the community from literature published during 1946–July 27, 2018. In pooled analysis, we found no significant reduction in influenza transmission with the use of face masks (RR 0.78, 95% CI 0.51–1.20; I2 = 30%, p = 0.25)”