There are some Dwarf Rabbit Breeds the smallest seem to be Netherland Dwarfs at 2 - 2.5 pounds (0.907 - 1.134 kg). Though one Wikipedia article claims weights as low as 500 g (1.1 lbs) are possible, not sure I believe this is likely for an adult rabbit. With 1.5lb to 2.6lb (700 to 1.2 kilos) being more likely.
I am not finding any quality reliable references at the moment, but small rabbits usually get to full size in 5 - 7 months, with large rabbits taking up to 18 months. Rabbits are old enough to breed at in the 3 - 8 month old range, and have generally reached 80% - 90% of the full size at this time. Obviously it is important to separate by gender around 4 months, lucky the boys tend (tendency not a rule) to mature a bit slower than their sisters.
In Summary it is possible to find a "rabbit that doesn't grow more than the size of a hand". But it is unlikely to be a crossbreed, it would likely be from a dedicated show breeder. The smallest rabbits that come into the organizations that I volunteer with (see my profile) are around 3 - 4 pounds full grown.