Since you want it client side, that indicates you want it for server play. I'd recommend against this, most server moderators don't want players doing this. It could net you a ban.
If you are the server owner, you can just use command blocks.
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hi there guys
I have a question: do you guys know if there is a mod where you can make a message and it is written in chat repeatly every x seconds
it has to be from the client side and if it doesn't exist someone can maybe make it. it doesn't sound that difficult
Since you want it client side, that indicates you want it for server play. I'd recommend against this, most server moderators don't want players doing this. It could net you a ban.
If you are the server owner, you can just use command blocks.
WARNING:
My output of snark depends on your output of stupidity.
My patience wears thin on strawmen and lies.