Not really. Retinal detachment usually happens when people with high myopia are playing intense sports or get a hit on the eye. If you are careful enough to protect your eyes from external force, you will not get retinal detachment.
Not everyone with high myopia will get retinal detachment, but the higher the myopia is, the higher the risks are. So the risk at -12.00 is a fair bit higher than the risk at -6.00. Intense sports can cause retinal detachment easily for people with high myopia, so you should be more careful when playing sports.
People with high myopia may have a higher risk of retinal detachment. But not all people with high myopia will get retinal detachment. Most people with high myopia have no problems. If you get regular eye exam, there is no need to worry about it. Once you get any symptoms, you can go to see your doctor immediately.