Theres someone working on a FSX Space Port program, but it wont work on the MSFS new version because it is limited to a 25 mi ceiling or maybe it was 250 mi, either way not enough to get actually anywhere other then orbit.
Kerbal Space Program is pretty good for what you want I think. Theres a free add on called real solar system that will give you the sun the moon and the stars instead of their default solar system (which is okay as well). Plus you get to actually build your rockets and space plane. Its older so it probably on the pretty cheap side by now, you can find it on the web or on steam…