Trimming a H265 video using FFmpeg and getting this error: “Unable to find a suitable output format for ‘output.h265’ output.h265: Invalid argument”

I am using below FFmpeg command for cutting/trimming H265 video for specific time interval. But I am getting this error:

“Unable to find a suitable output format for ‘output.h265’ output.h265: Invalid argument”

ffmpeg -i input.h265 -ss 00:00:20 -t 00:01:00 -c:v copy -c:a copy output.h265

How can I find solution for this issue? I am using FFmpeg version 4.3.2.