The gap you are seeing is because the rubber strut bushing is worn out. It might be the springs are tired too. See Figure 10, green arrow Volkswagen Jetta Mk4 Front Strut Replacement | Jetta Mk4 2.0L (1998-2005) | Pelican Parts DIY Maintenance Article
If you are looking to lower the car (I've never done it), I belive you are looking for "coilover" springs.
If you are looking to lower the car (I've never done it), I belive you are looking for "coilover" springs.