Eager Loading EF Core 2.1 Load only First Level

Well, I need a lot of help! I'm having a C # WebAPI project as per PRINT below:

The problem is this: I need to access the data of navigation properties created by EF Core 2.1 DBFirst, but only the first level! What is happening is that LOOPS are occurring because in relationships, there is actually INVERSE ACCESS as you can see in the classes above, I tried to use LazyLoading but with no success! The amount of information generated in these queries hangs against the VS17 Community that I am using. I also tried to use (Eager Loading) as shown below:

public new IEnumerable<Item> GetAll()
{
    return _dbContext.Set<Item>()
        .Include(x => x.IdEmpresaNavigation)
    .AsEnumerable();
}

I'd love your help to know what setting is needed to fix this problem! I am already 3 days with this obstacle in my life! Many thanks and happy 2019