How to only reduce bitrate on 4k videos

[eldruida]

Hi, greetings from Spain. I'm a newbie Hybrid user, so forgive my ignorance. What I need is just to reduce the bitrate of 4K videos while preserving their characteristics (HDR, Dolby Vision-less important, profile, space color, etc.) without changes. I don't care about audios or subtitles, I just need to change the bitrate. I would appreciate if you could indicate a setting or a guide to be able to do this. Thank you very much in advance.