I am a Facebook page admin. I want to know that is there a way I can tag my page's followers or people other than my friends in photos and videos that I post on my page?
It is not possible. You have to be friends with someone on your user account to tag them in photos on your page.
All that I can suggest is friending them and then tagging them or send them a message letting them know they are in one of your photos and then they have the option to do it themselves.