I have a lot of artwork I purchased from a website, but the artist who drew the game assets is unavailable.

I need to create additional artwork which fits with this style, but I am not an artist- nor do I have any idea of how artists work.

Obviously, the solution is to find a new artist, who I can pay to draw this artwork while keeping it to look at certain way.

I am scared of wasting money though. I don't want to contract an artist, only to find out it is extremely difficult for someone to match another person's art style. I don't need it to be identical, I just need it to be cohesive. I also want to know what I'm asking of people, before I ask them. Artists are workers just like me, and deserve to be understood when contracted.

As an artist, is it extra difficult or time consuming to alter your artwork to match a certain style? Does it require a lot of talent to make a cohesive piece of art?

To be specific, I am talking about structures, such as 2D symbols of towns for a map. They all have this "gritty" penciling effect to them and lots of saturated colors, which is what will be required when I say "cohesive". Along with looking like the architecture belongs in the same world.