A community is a thing that evolves. It is created by the people. When there are issues within the community, you can always ask them. For example, on my community c/Games there was a discussion about memes. I simply run a poll and the community decides. Now you cannot do that for every little thing, but it is always a option.
Regarding the NSFW. There are clear rules as stated in de official rule page. These rules are site wide and the same for all mods:
Do not post about inflammatory, controversial subjects without a Content Warning. Ideally, you would not post about inflammatory subjects at all. However, it may be acceptable to do so in some cases, but it is never acceptable to post inflammatory content without hiding the content behind an appropriate Content Warning.
Do not post any type of nudity without a Content Warning.