How can I reduce file sizes of all my photos and videos for storage?

I know for photos i could throw them through something like Converseen to take them from .jpg to .jxl, preserving the quality (identical visially, even when pixel peeping), but reducing file size by around 30%. What about video? My videos are in .h265, but can i reencode them more efficiently? im assuming that if my phone has to do live encoding, its not really making it as efficient as it could. could file sizes be reduced without losing quality by throwing some processing time at it? thank you all