A rare case that addresses the grip issue is iPhone X Case (5.8"), DesignSkin [Corner] : Shock Absorbing Ultra Slim Light Thin Edge Cushion Bumper Protection Hard Cover Simple Basic Minimalist Case for Apple iPhone X (Matte Black) https://www.amazon.com/dp/B076HHQMKZ/ref=cm_sw_r_cp_tai_w8GCAbDSZZCDV
I’ve had my eye on this one, but the reviews are meh. I’m sticking with my Pitaka MagCase. I went back and forth with it, but now love it.