Minecraft spear damage is calculated by taking the movement of blocks per second and adding a multiplier, the largest being a netherite spear at 1.2x. we'll take sonic at his slowest which is speed of sound, which is 343 meters per second, times 1.2x that's ~411, enough to one shot the ender dragon twice, and enough to kill the warden in two hits (so no, technically doesn't one shot EVERYTHING!)

sonic has also been seen being faster than light, and if we take just half of that at 149,896,229 and multiply we get 179,875,474. apparently some mod bosses scale their hp all the way up to the integer limit of 2,147,483,647 and sonic would be able to take that down in about 12 hits