Theoretically it is possible but there are some hard limits in what range of speeds is possible. Simulating at over normal speed requires more CPU power to process more physics updates (the other alternative would be to make physics simulation steps depend on the speed which is a massive pain and generally always recommended to not be done). And simulating at lower speed will at some point make the gameplay really choppy. So there is a hard lower and higher limits. I haven’t tested but I’d guess something like 0.5-3x speed would be a doable range.
Not to mention how many places in the game would need to be verified that they work correctly when the logic step size is increased or lowered (though I estimate this to be pretty minor compared to the above points).
Would anyone really want to use such a slider though? It’d increase the amount of time Thrive takes to complete a lot. Or alternative it’d make things harder to react to. My guess is that everyone would crank the slider to max speed if they weren’t going for a toxin shooting build, because that just lets’ you play faster. So to me this feature seems like something everyone who knew, would just always crank to max speed so it wouldn’t be very interesting gameplay element (as there’s no choice to be made, just crank speed to max to reduce waiting times).