Yes!
It should require fewer draw calls. Be careful not to merge everything in the project, though, as if any part is on-screen it will render the entire thing.
Do not merge the entire level. It will be very bad for optimization. Think of it as a cookie! Merging chocolate chips, flour, egg. Then baking it you have a cookie.
Don’t merge the entire bake sale. Merge the level blockout- the floors, the ceilings, the walls- but don’t merge the table and chairs inside with it. You want that stuff to be de-rendered when unseen.