Is it legal to drink outside an appartment complex?

This is probably a state and local issue in the US. Generally it is not good to drink alcohol in public view, except at certain special events perhaps, and there may be various local laws as well as local customs. Generally, port cities are more liberal, while more agricultural areas are the most conservative. There may also be rules or contracts that affect the renters and renters guest's rights to do certain things on the appartment complex property. While these are not laws, they can have the force of law.