I don’t think the movie is as clear as it could be about Finn’s force sensitivity being The Secret, since many have interpreted it as being in love with Rey, but it’s definitely pretty blatant that he is force sensitive. When Jannah talks about their mutiny, she calls it “a feeling” while the force theme plays and the shot places emphasis on that line, then Finn starts telling her about how the Force made it happen and brought them to that point.

Then with the command ship it’s the same theme, and she asks how he knows, and the music stops and he says “a feeling” again. It’s a very blatant callback, the only way to make it more obvious is for him to declare “the Force is guiding me!” Him sensing Rey’s death is just more evidence on top of that.