AmazingjoysSeamless Slip Shorts Women's Smooth Slip Panties for Under Dresses

Are these suitable under thin trousers such as culottes or other see through fabrics?

I am a size 18-20 so am ordering a 3xl. Will they fit ok? I prefer to get a slightly bigger size for a less tight fit.

Would you kindly measure the inseam (from the crotch to the bottom of leg) because i want to wear them under a mid thigh dress.i'm 5"3 thank you

Are these stretchy?