You’re in the right location for a start.
Firstly find a single one. That will be hard because if he is single it’s because he’s just divorced (baggage and skint, pretending to still have money), or too much of a playboy to marry.
You’ll need to be highly attractive in a way that makes you stand out from all the other highly attractive women. And I don’t mean in a you’re a redhead in a sea of blondes type way.Natural poise and intelligence would give you that edge over the other women perhaps.
Play very hard to get, and the long, long game. New rich men are already entitled so think they can buy whatever they want. Make them earn it.
Get yourself seen. You need membership to the yacht club, casinos, tennis clubs, top restaurants, etc (I’m assuming you’re in Marbella or Monaco) so muscle in with other women also in all these clubs and Friend Up.
Be gracious and genuine always, and have an interest that makes you interesting to men. Not shopping or sports necessarily, something more unusual, preferably practical rather than creative. Go on a sailing course, plenty of single older men in that world. Drive a ratty old Land Rover instead of a slinky sports car.
Never mention children or marriage as they’ll run a mile before the starter pistol.
It’s completely possible, but those ‘plain boring wives’ probably weren’t any of the above, because this is new money you’re talking about going after, and those men started from scratch with nothing and already had a loving woman.
If you want single, old money, hang about down the sailing clubs or become an art gallery assistant. Men who are allowed to buy their own expensive interior decor are definitely rich and single.