Lately I’ve been looking into hypothetical models and articles about spacetime-warping, exotic-matter tech, designs for sci-fi stuff like warp bubbles as well as for things like artificial gravity and other uses described in papers like this one.

From the conclusion paragraph:

We designed an artificial gravity field for a spaceship, but using simple stress-energy distributions one can readily design “closets” that are larger on the inside than on the outside or “refrigerators” where time runs slowly (to keep food fresh).

Both those two alternate designs sound exactly like the sort of thing I’d like to implement in a fiction setting, following the ideas described in that artificial gravity paper above; but this is the part where I should note I’m really no physicist and could only confidently comprehend the parts of the article in plain ol’ English.

So my main question is, are those two designs (the larger-interior “closet” and the time-slowing “refrigerator”) actually possible as two separate different designs like how they’re listed there, where the closet can have a larger interior space but no time dilation compared to the outside, or the fridge has slower time passage but could still be made with a regular interior volume?

Or would a stasis-box/TARDIS-closet made with exotic spacetime engineering like described still have to function as both things, meaning anyone hoping to live in that expanded closet would have to live with its time-slowing dilation too?