Premiere Pro can handle H.265, but whether it can perfect handle H.265 depends on your hardware decoding ability of your computer.
Here’s a quick rundown of well-known hardware that includes dedicated HEVC decoding blocks, which definitely support efficient HEVC playback:
Intel 6th-generation ‘Skylake’ Core processors or newer
AMD 6th-generation ‘Carizzo’ APUs or newer
AMD ‘Fiji’ GPUs (Radeon R9 Fury/Fury X/Nano) or newer
Nvidia GM206 GPUs (GeForce GTX 960/950) or newer
Other Nvidia GeForce GTX 900 series GPUs have partial HEVC hardware decoding support
Qualcomm Snapdragon 805/615/410/208 SoCs or newer. Support ranges from 720p decoding on low-end parts to 4K playback on high-end parts.
Nvidia Tegra X1 SoCs or newer
Samsung Exynos 5 Octa 5430 SoCs or newer
Apple A8 SoCs or newer
Some MediaTek SoCs from mid-2014 onwards