Depends. Lefties often do and are, surprisingly very vocal about their beliefs. A subtle "Fuck racism, fuck capitalism, ACAB" goes a long way. If you are looking for men as a woman, you're gonna get a million likes on any app either way, so just look for people that fit you. I'm personally not opposed to dating some normie-liberals and get into prolonged discussions about economics and capitalism on my first date, so your results may vary.

Apps like OkCupid ask more deeply about your beliefs and you can filter pretty successfully for leftists.