For that, you could read up on mask-wearing here, which has been a thing for a long time--well before covid hit, which, since masking was relatively common, it was very easily adopted even further during covid.
And then some (foreign?) news person saw/noticed that everyone was masking, articulated that, and their (and their audience's) conclusion was, "wow, the japanese are so conformist." Not a correct assessment/interpretation at all.