Small Junkheap is one of the Junkheap brothers.
Age Of Extinction film
Junkheap was in a KSI factory of Beijing when Galvatron took over and was possessed with his brethren. Along with the other prototypes, he traveled to Hong Kong to detonate the Seed. When helping take the city, he split into three components to cover more ground.
The Last Knight film
Small Junkheap episodically shown, where fights with Big Junkheap and Medium Junkheap in Hohn Kong, in the stories of Sir Edmund Burton, about what happens in the absence of Optimus Prime.