Dont know if its possible in 4.15, but im in 4.23 and heres the deal there:
The Actor class has by default a Name type array variable called Tags, which stores all gameplay tags this component is assigned to. You can call it and manage it the way you want it like its a simple array (incl. at runtime ofcourse).
Same for Actor Components, but instead they have by default a Name type array variable called Component Tags