Looking for a basic admin bot which can PM new channel visitors a greeting, and announce a topic every X hours

Does anyone know of a bot which can do these two basic things? I want the bot to send new channel users 2-3 private messages with some Telegram tips, and a list of related channels. And, I want the bot to be able to maintain a channel topic somehow, such as announcing the topic once every 24 hours and allowing certain people to change it, for example.

Anyone know of a bot that does these things? Otherwise, maybe I'll make one...