This is all I've found on sliding which has actually been adjusted recently due to the Pickett fake.
4.1.3.r
When a ball carrier obviously begins a feet-first slide.
A.R. 4-1-3-III
Third and 10 at the A-35. Quarterback A11 sweeps to his right and goes
into a feet-first slide to give himself up. When he starts his slide, the forwardmost point of the ball is at the A-44, and when he comes to a stop the
forward-most point of the ball is at the A-46. RULING: Fourth and one at
the A-44. The ball is dead at its forward-most point when he starts his slide.
There is no mention of sliding to give oneself up. Slides have happened with no defenders around. The rule is meant to stop play as soon as the ball carrier starts the motion even if they don't slide (now after the Pickett fake). Here is an example of an NFL one:
https://www.nfl.com/videos/mckinnon...ide-at-1-yard-line-to-help-chiefs-run-clock-d