How? Can someone send me a guide or write the steps?
It depends on your environment.
You can schedule a message with cron and some endpoint.
or, you can use a scheduler depending on your using programming language.
Redirect line app
Line (liff) login issue with default browser
Line message API
Number of Audience count created is different from number of audience count in job.
How can I get the source channel in LIFF APP ?
[iOS & Android] Line auto-login opens "redirect_uri" in a new tab
Maximum response time for broadcast
Auto-response message in text mode not more working
LINE Message API webhook url Can I set up more than one?
Error connect EMFILE from LINE API