Sure, Kate Middleton's preferred way of sitting is the Duchess Slant, but when it comes to royal events, Meghan Markle has her own regal way of demonstrating good poise and posture: It's called the Sussex Slant.
Coined by etiquette extraordinaire (and Beaumont Etiquette founder) Myka Meier, the Sussex Slant is a very slight variation on the seating position shown off at many a royal gathering by Kate.
To pull it off, you need to cross your legs at a 45-degree angle, then rest one leg on top of the other with your ankles placed together delicately...and indefinitely. (Or at least for however long the royal event company meeting you're attending lasts.)
The benefit of a position like this: It helps you sit up straight while simultaneously preventing a peekaboo moment if you're wearing a skirt.