Breed and size do not really matter when it comes to bonding compatibility — there are absolutely instances of rabbits of different sizes/breeds bonding successfully and also examples where it is unsuccessful (but it’s not likely that their difference in size/breed is what the bond’s success was contingent on).
As a bonder, you always want to intervene when there is imminent risk of injury to either rabbit. If you’re attempting a bond that involves a significantly larger rabbit, I think it just obligates especially intentional care and mindfulness in quick, effective intervention during bonding sessions — this means no casually leaving a session for a second or not coming prepared with gloves or things to stop fights. These are ordinarily things you want prepared for any bonding session, and also it is extra important when it may be easier for one rabbit to more significantly harm the other.
Rabbits don’t playfully bite or swat at each other, so in terms of unsafe behaviors between bonded rabbits, that’s not an issue. The only ‘issue’ I foresee is the uncommon situation where humping is still a big part of the dynamic and the humper is a significantly larger rabbit who has a tendency to face hump, in which case the suggestion would be for the owner to gently stop that when it happens. Altogether, I don’t see any reason to objectively decline trying a bond based solely on size/breed difference.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.