there are 2 ways to do this basically. one easy, one harder
1) The Easy Way:
Is just map transitioning via either a reach marker in a turboshaft, or an invisible interact inside it
2)The not so easy way:
This is achieved firstly by creating an entirely custom interior map. you still either have the reach marker or invisible interact in the turbolift, but instead of getting a map transition screen, you actually have objects set to go from invisible>visible at your interaction and vice versa. An example of this can be found as I recall in Alimac30's Spirits of Ramak Nor. While this is the cooler of the 2 options, there are issues with it as well, you have to build the set(s) which are time consuming and limited to 500 objects per map.