It's worth noting here the efforts of the "Gerald Undone" channel on YouTube. This is a man who has done all the hard work for our benefit.

In essence, have constant quantization in your encoding (if you have that option to futz around with) and add just enough sharpening that it's starting to look over-sharpened, then upload that encoded file to YouTube. "YouTube makes everything softer."

There's a little more to it, and the video is worth watching at 3:53 onward.

Beat the Compression! How to Get Better YouTube Uploads - YouTube

Andrew

I basically agree 100% with his comments. I do a lot of 4:3 SD interlaced footage to progressive HD upscaling. This requires a lot of re-scaling, processing, noise reduction, re-grading and audio processing. as seen in this sample. Here, the detail radius is set to 38 in Resolve. 38 is generally considered a pretty severe amount of sharpening. But when encoded to H.264 it gets 'rounded' down quite nicely for, in this case, YouTube.

Chris Young

British TV Classics - Video Restore Process Sample - In answer to viewer questions. - YouTube