Darth Lucas said:
Handbrake can do lossless encoding by putting the RF value at 0, but takes a century and a half to encode.
And it's not a very useful thing to do:
https://trac.handbrake.fr/wiki/ConstantQuality
https://mattgadient.com/2013/06/20/comparing-x264-rf-settings-in-handbrake-examples/