Did Broly go Super Saiyan 4?
Similar techniques. Broly’s legendary variation of the Super Saiyan 4 form, simply referred to as Super Saiyan 4 is a form utilized by Broly in several video games. It was accessed from the Legendary Great Ape form. It also has a full power variant to the form.
Will we see SSJ4 in super?
Ssj4 is non canon, and technically, even if it was, he hasn’t gone ssj4 yet because Super takes place after Z and well before GT. Also I think Toriyama has stated that a perfected base super Saiyan is stronger than future transformations.