I haven't been on a cruise since the virus hit but I can give you my experience up to a couple of years ago.
Carnival has forced smokers outside to one or two designated deck areas. It can get mighty hot outside, or cold, or really windy. Carnival used to have nice cigar lounges but did away with them so as not to offend the sensibilities of non-smokers.
Celebrity places smokers on the same level as lepers. Nowadays they may just toss smokers overboard, who knows.
NCL was the best, within their limits. The limits being cigar lounges. Some ships had them and some didn't. On ships with them, the lounges were quite nice. On ships without them, it's the outside designated deck area for you. And where the lounges used to be the domain of cigar aficionados, now they've become the refuge of cigarette smokers.
Not sure if this info is still current or not. I'd assume most lines have the designated areas that Carnival uses and where smokers are tolerated but not really welcome.