No, in my understanding you basically convince as many co-workers as possible to join the union together. Ideally the majority, but essentially you just need enough that they can’t fire and replace you all overnight… Which means, it has to be enough that the rest of the staff can’t cover for the union members for a few weeks or months without drastically slowing things down

You could probably reach out to a relevant union rep to get more info- there’re legal processes to help with this, like protected voting if enough people want to join a union or not, that probably varies by where you live and I only know the basics