You typically can't make something "better" with a lower original source but Sony does the best up-scaling of the current TV manufacturers.
Each channel from your source could be different.
I've tested content from OTA 480, 720 and 1080 and even channels differ from each of those resolutions.
My Comcast box is set to 4K output (nothing is being broadcast in 4K BTW) and each channel is different, again based on source.
DVDs look good from my Panasonic UHD BD player as well as BD discs, but that player is up-scaling.