Can You Apply From Outside the United States?
Yes, potentially.
You do not necessarily have to already be living in America to begin every employment-based immigration process.
For someone outside the United States, an employment-based immigrant process can eventually involve consular processing through a U.S. embassy or consulate.
For someone already legally in the United States and otherwise eligible, adjustment of status may be available in appropriate circumstances.
Which process applies depends on your immigration situation, visa availability, eligibility, and other factors.
The State Department explains that employment-based immigrant cases can involve employer petitions, visa processing, interviews and ultimately entry as a permanent resident when approved.