DLNA device profile / Transcoding to lower resolution

I would like to have a DLNA profile that has a simple task. If the file is at or below a certain resolution - do nothing, send the file as-is. If the file is above a certain resolution - transcode down to a set resolution.

The specific device doesn’t matter, it can do this for any and all clients, audio never needs to transcode, the format will always be h264 MP4 or h265 MP4 and if transcoded will be to h264 MP4

I am finding the emby (and therefore jellyfin) documentation difficult to understand so I’m not sure if what I want is possible. I managed to set this up easily enough with serviio, but couldn’t get it to hardware transcode so I am sort of stuck in the middle.

I am trying to set things up for a family member, and if I can get the above to work it would mean not having to buy any new hardware which would be great