Still unsure about ryanair bike carton measurements after talking with customer service. Anyone here have some experience?

I want to buy a flight from brussels to Glasgow this august, it will be my first time flying with a bike. The ryan air website tells me that bike weight is supposed to be under 30kg, but otherwise does not specify the measurements that my bike box can have. I asked cs if they knew if the measurements are 120x120x80 just like oversized luggage, or if I can take literally any carton I can find, regardless of size when I pay for bike lugguage. CS said that there are NO limits at all, which sounds iffy to me…