Lowering the resolution to match the typical TV resolutions is sensible but beyond that trusting the codec is always the better way. The codecs will adaptively compress portions of the video differently. The top left area that's in shadow for the next 30seconds? Maybe that areas effective resolution can be lowered? Etc. They can do things like this!

If you change the resolution or color space of the entire file you do that without consideration to where the extra details might have been needed.

So resolution should match typical output resolutions exactly and from there it's all on the codec.