Replace specific text with texture from chat message

I want to re-add a feature from one of my favorite mods, which is emojis! And it basically works like this: ":<emoji name>: is replaced with <emoji texture> related to <emoji name>". Unfortunately, that mod is outdated and I want to add it back for 1.21.8. The problem is I don't know what procedure blocks and/or other things I need to recreate the feature to use. Can anybody help please?