Format-Transforming Encryption (FTE) is what you're looking for--it ensures the resulting message isn't vulnerable to cryptanalysis techniques while enabling encoding of a message in arbitrary formats [0], including a blog post or text message. The authors of the source use it specifically to hide messages in semantically-correct network protocol packets, but it applies just as well to text.

[0] - https://dl.acm.org/doi/pdf/10.1145/2508859.2516657