It is usually based on turnover, however none of them state what is required anymore. Coral used to have a page on site explaining the requirements for each level although most people once they reached it were restricted & promo banned very quickly.
It isn’t something you should really aim to look at achieving – if you become a VIP anywhere just see it as a temporary bonus.
There is the possibility that VIP schemes will be closed down in the near future with the current discussions ongoing in the industry with the UKGC / Government / Anti-fun activists.
@pnr8uk Rewards4Racing is nothing to with Coral. You can earn points at Bet365, Betfred & Betfair as well.