Unfortunately, the Pi3 is too weak to decode HEV in software, and it can’t do it in hardware either. Same for the 3+ as well. The excempt for this is 720p24 or 720p30, that’s the most it can do in HEVC/H.265. If you’re willing to overclock and install custom heatsinks, you might be able to squeeze out some 1080p24 with low to medium bitrate.
https://discourse.osmc.tv/t/pi-3-h265-playback-experience/
Get a Vero4K and enjoy UHD. 