Neither working full time or taking only online courses prevents you being classified as a full time student.
Why do you ask; that is what tax benefit are you seeking or what tax negative are you trying to avoid?
References:
https://www.investopedia.com/terms/f/fulltimestudent.asp#:~:text=According%20to%20the%20IRS%2C%20ful....
https://www.usnews.com/education/online-education/articles/2016-01-29/decide-between-part-time-full-....
