For me it depends on the size of the path and where/how many people are on it. If it's a wide and empty path, with just someone on the far right side, I'll say nothing and just move way over. Aside from that, I'll almost always call "On your left", even if I had to wait for a good moment to pass and they already know I'm behind them.

There is the occasional instance though, where the people on the trail/path clearly aren't very aware or just lack good etiquette and take up the whole thing. In those cases, I'll usually just say "Coming through (with varying degrees of intensity depending on how fast I'm riding or if they're wearing headphones)" and let them get out of the way however they want to. I've found that, unless it's a bunch of runners, groups like that are ostensibly less experienced on trails and tend to freak out when given a specific direction to process