Post reach and post engagement do not go hand in hand. This screen shot shows the stats for two posts that ran on the same Facebook page. The orange bar and corresponding number show the total reach of each post. The numbers in the column on the far right show the total number of post reactions, comments, and shares.
The first post was just text. The second was text with a photo and some tags of other pages.
If you believe that social media is only about gimmicks and knowing the "tricks", then the second post should have gotten way more engagement. After all, it apparently made the Facebook algorithm happy and was thus shown to many more people.
But it seems that what you post matters just as much as (if not more than) how you post it. Hence why the first post, which was shown to fewer people, had way more likes, comments, and shares than the second one.
Despite the algorithms, hashtags, and boosting options, you are still communicating with people.