If a police officer comes to your door and asks you to step outside can you refuse And if you do refuse can he then forcably pull you outside?

You can refuse, and a law enforcement officer cannot lawfully enter any structure or vehicle without a warrant, probable cause, reasonable suspicion (under certain circumstances), or exigent circumstance (emergencies). However, keep in mind the number of largely innocent people and minor offenders US LEOs have shot and killed with no charges brought. This will continue so long as the American people continue to permit our laws to be subverted.

Closing thought: law enforcement officers in the US are more accurately slaves to our laws, all by their own volition, not defacto royalty above those laws. Hold them to the standard they should be held.