To the extent the site has an overarching culture, it's right-wing. There are boards outside the overarching culture (I said there were only "few" earlier, but I don't know if that's right).
/tech/ is the largest technology board. It's part of the overarching culture. It has a clear political leaning, even if that leaning is not part of the rules or the stated topic or the moderation policy. If you look at /tech/'s catalog, there's threads like "Stallman Going SJW on us?" and "Apple - FULL ON JEWMODE".
/christian/ has a /christian/pol sticky that encourages people from all parts of the political spectrum to post but seems to have primarily right-wing posters in practice.
/lit/'s second non-sticky is "Race Realism/biological determinism Books".
Not everyone on those boards is right-wing, of course. Being right-wing isn't their defining characteristic. And there are other boards that don't have this.
But boards with a politically neutral moderation policy that get cross-posters from other boards are likely to end up with a culture that's right-wing.
/leftypol/ is explicitly left-wing, so even its cross-posters are left-wing. Some smaller boards mainly get users through other means, so they're decoupled from the site culture. Non-English boards might be insulated as well, but I've never used any of the large ones so I can't tell.
Large boards tend to lean right though.