Realism is one of the better tools for a cover up, because a realistic image already contains deep shadow, and shadow is where an old tattoo can be hidden instead of fought.
It is not magic. What is underneath decides how much freedom there is, and any artist who tells you otherwise before seeing it is selling you something.
Rarely with realism alone. Solid black leaves nothing to work with, and that is the case where laser first is the honest answer.
In the right light, sometimes, faintly. Anyone promising you it will be completely invisible from every angle is guessing.
It has to be darker than what is underneath in the places that matter, which usually means the design is built around where the old ink sits.
Often, once it is fully mature, which usually means a year or more. Scarred skin takes ink unevenly so it has to be seen first.
Requests go straight to Federico, not to an agency inbox. He answers from his own address.