The center 9 engines could gimbal

*Starship for scale

This is how 1000 Merlin 1D engines would look like in a 35 m diameter rocket. Also if it had the same height-to-diameter ratio as the Falcon XX concept (105 m / 10 m) it would be 365 m tall. (this would make it the same height as the world's 74th tallest building). But if we calculate with Falcon 9's height-to-diameter ratio (70 m / 3,7 m) it would be 662 m tall. (this would make it higher than the world's 3rd tallest building).

Credit to u/Ordinary-Ad4503