Is in possible to play 4k\8k content with h265 codec?
No. That’s not possible. Two problems:
The Pi can’t decode H265 in hardware, so it has to rely on software decoding. This is slower, but apparently doable with some limitations but not supported in info-beamer.
The Pi can generate a barely usable 4K HDMI output signal but no 8K signal. FullHD is the only reasonable output resolution. The hardware decoder for H264 is limited to 1080p60, so even if you manually set the Pi to a higher resolution you can’t play anything above FullHD.
What you can do is use multiple Pis can play a chopped up video across any number of Pis. That way you can play 4K and 8K. See Info-beamer at the NEC New York Showcase as an example of such a setup.