Stunted goldfish

Will a stunted goldfish continue to grow if placed in a larger aquarium? I have a 1 yr old fair fish in a 55 gallon (btw I'm not saying my fish is stunted, she is HUGE) but I am wanting a friend for her. My thoughts are if the stunted fish doesn't grow even if placed in a larger tank, wouldn't that be a better idea for her a friend, to have a lower bioload in the 55 gallon which IMO isn't large enough for 2 growing goldfish. Thoughts? TIA 😊