A few days ago I went to Changshu, a city near Shanghai, with my high school friends. To tell the truth, there was little of interest there, and so once again I was reminded just how deceptive online posts can be. People will post fantastic travel photos and describe the local food they eat with magniloquence. My friends, always keen followers of online tour guides, have led us to disappoinment quite a few times. Yet they never tire of this pastime. We’ve also found that apps like Photoshop permit you to beautify your photos, and thereby transform them into splendid misrepresentations of reality.
Note that "people will post" is not about the future. This use of "will" expresses certainty or habitual nature, not time frame.
There is no need to say "they've eaten". It's not wrong, but simple present tense works fine: "people will post ... they eat ...". The meaning of "will" here is similar to "do".