I assume it is a smart tv with apps....
If you do not have Netflix 4K I would pay the extra few bucks to subscribe. You get 4K movies/tv on up to 5 devices for $12.99 a month I think.
YouTube has a ton of awesome 4K videos. I built a 4K playlist on YouTube and use it to show off my UHD HDR videos....all free. The GoPro 4K stuff is amazing.
If you have a XBox One or PS4 the up-scaling will make games improved and crisp. I usually keep my tv in dynamic video mode for awesome color saturation.
I have a 65 inch UHD HDR Samsung 2016 4K tv and love it.
ENJOY!