ProClip is now offering new models of their in-car phone mounts specifically for the Lumia 950 XL. The cradles mount into your car, letting you place your phone higher up easier access and use of features like navigation. ProClip offers both a standard phone mount, as well as a charging mount with an integrated USB charging cable.
Both mounts let you set your ideal position, swiveling up to 20 degrees in any direction. Additionally, you can choose between portrait or landscape orientation, depending on your preference. With the charging mount, you get an integrated USB-C power cable, which plugs into an included car charger. The charger provides 10 watts of power and plugs into any standard 12-volt power car outlet.
Note that if you're using a Mozo replacement back cover with your Lumia 950 XL, you won't be able to do so with either of these mounts. ProClip does make a universal mount that should work, and that sells for $39.99.
You can grab ProClips Lumia 950 XL mount for $34.99, and the charging mount for $79.99.
Thanks to Colin for the tip!