There has been a SpaceX Superheavy Starship rendering with two additional side boosters. Each side pusher will have 31 Raptor engines like the first Super heavy stage.
The SpaceX rocket with this configuration will be able to launch around 250 tons in one launch versus 100 tons of SpaceX Superheavy.
Kimi Talivitie is the original creator of the SpaceX Super Heavy Starship metal rendering. Others seem to have added a metallic Super Heavy boosters.
The following is a rendering of SpaceX Super Heavy Starship metallic with a side amplifier.
The following is the previous Kimi Talivitie SpaceX rocket rendering.