There has been an interesting Martian Policy mod by Silva which aimed at representing the Colony's administration and internal policy choices. it's unfinished as far as I know but maybe there's hope to see a more fleshed out version of it one day as an official pack.
Foreign policy is already modeled in the Space Race expansion. Some may say it lacks depth but it is what it is. In regards to relations with Earth, I'm no lawyer but I think international treaties as they are today don't allow any nation to formally expand into space. Your colony would therefore be politically independent from the start. The goal to make it economically autonomous is already at the base game's core. Totally breaking free and becoming a rogue colony relying on space piracy could be fun but I don't think it's in the style of the game, nor do I see what the Martians would have to gain. Maybe an idea for a mod?
There is also the "Last War" mystery where a major war breaks out on Earth and your colony is tasked to provide goods to "work towards peace", which is probably your sponsor's way to say "support one side of the conflict", but from a Martian point of view, the only goal is to prevent Earth's civilization to throw itself back into the Stone Age in order to keep it as a viable commercial partner. The idea to meddle into Earth's political affairs for whatever advantage it could provide could be expanded upon, but it's probably best to leave it to modders.
I don't think Surviving Mars is suited to represent the world at a late colonial stage with around one billion or more inhabitants and a free market or post-scarcity economy. A "Martian Cities" expansion for Cities Skylines would be far better in my opinion. Someone already built a city on Mars with a heavily modded game:
For truly awesome floating cities I think we would need a whole new game. According to some, the Venusian upper atmosphere presents ideal conditions of temperature and pressure for a viable suspended colony, so maybe an idea for a future Surviving Venus?
