You don't need a dock - you can use a simple thunderbolt/USB-C to HDMI or displayport adapter.  
I have a Dell G15 5520 laptop but there is no DisplayPort output so I can't get 165Hz from my Dell G2722HS monitor. Which dock should I buy with USB-C output to get 165Hz?
G15 5520, G2722HS, no 165Hhz, dock?