Do you mean something alon

Do you mean something along the lines of the effect I used in

at about 1:00?

We took the action that we wanted to be in regular motion (singing) and in real time had the person sing 8 times slower than normal. We then took that footage into our editing program, and sped it up to 800% (8 times faster). The singer then appeared to be singing at a normal speed while the world around him was moving super-fast.

You simply need to isolate the action that you want in real time, and make them perform that action at a slow rate of speed, then adjust your speed in post. You can experiment with how slow or fast to get the best effect.