Note: I've only tried it in 1.16 and 1.8.9, does not work in 1.8.9, but not sure about other later versions.

If I remap the Attack/Destroy or Use Item button (Default left/right mouse button) to another key such as "K" or another letter, when holding the key down, it rapidly clicks at 30cps. With left click this spams a lot of hits, and right click can place blocks super fast or throw 30 snowballs per second, etc.