Organically...
There was some dude who wanted to "promote sports" and he did that by making over 100 communities that all had individual mod bots who posted constantly
All that did was get everyone to block any sports posts because it blended in with spam.
Make a couple posts for big stuff, but if you don't get engagement, the answer isn't to increase quantity, it's to increase quality.
Like, post a thread for an important match, but expect most comments to be made after the game. And your sport has 20 games a week, posting 40 threads one for each team just dilutes it.
Maybe do a weekly recap thread or just post highlight videos to draw people in.
Bot posting is just going to end up as spam if no one engages, and everytime someone blocks it early for spam, that's a user that may have stuck around and contributed for years if it had a better start