Click bait sorry. I haven't got a child starting secondary. I only have a lay interest in this from reading the boards over the years.
Of course I and anyone else would be totally unreasonable to turn down my offered school unless I already have a place at a private school or I really would be willing to home educate
Accepting an offered school does not impact your chance of a successful appeal.
Most areas you automatically go on the wait list for higher preferences but check rules for your area.
You can get appeals advice on the Secondary education board.