Cinematic Rocket Delta-V Rules

[GURPS Fox]

So, I've heard that there are rules for the various reaction rockets that make them more akin to the rockets used in cinema and/or games (like The Expanse or Battletech), and want to set things up for 'cinematic' rockets and a more realistic 'semi-cinematic' reaction drives.

I'm wondering because a setting that I'm working on would have present-day reaction drives to be considered 'semi-cinematic' reaction drives...