Is there a bot to collect posts from a large chat according to certain criteria?

Question

Bots

Hello! Google used, but did not find a solution that could fully satisfy the request.
The bottom line - there is a crowded chat with more than 4k messages per day. Some of these messages are useful, but losing them in a ton of flooding is easy. Messages can be both text and graphic.
What I would like: a user who wants to send a useful message can put, for example, a certain hashtag, by which the bot would find him and transfer this message to a private channel.
I would be glad if someone shared a ready-made solution or suggested how to implement it.