We’ve seen this already. Starship should be capable of at least 100t to orbit, which is about 40TJ of energy on orbit. The Little Boy was 63TJ, so accounting for losses, Starship flight test 1 was exactly what that would look like.

Do note that much of the energy was lost because most of the fuel didn’t burn, it just evaporated. The Beirut fertilizer explosion was 1/30th the energy, but all released at once.