To my understanding, engaging helps engagement. So if I see a post and I can think of something useful to say, I make sure I do. Though slow at first, I have the impression it helps. Plus the more you interact, the more instances see the involved users, posts, groups and instances.

Also, Mbin (the software my instance uses) and Friendica both support the equivalent of X/Twitter's retweets and Mastodon's boosting for both posts and comments (even if the OP's instance doesn't support it). So in my case, if I see something I like, also for the sake of engagement growth as I also notice microblogging folk are more engaged, I make sure to tap the boost button too. Maybe it'd help if more people did it?