In Germany, juvenile detention is up to 24 years. Juvenile law is also not that straightforward, if it’s applicable also depends on how “childish” someone still behaves. In some cases one can be 20 and still go to an adult prison, e.g. if they’re very violent and wouldn’t fit into the education-oriented juvenile detention. On the other hand, older people who behave very childish (e.g. because of a disability) will usually not be put into an adult prison and instead get something more therapy oriented similar to juvenile detention.
In Germany, juvenile detention is up to 24 years. Juvenile law is also not that straightforward, if it’s applicable also depends on how “childish” someone still behaves. In some cases one can be 20 and still go to an adult prison, e.g. if they’re very violent and wouldn’t fit into the education-oriented juvenile detention. On the other hand, older people who behave very childish (e.g. because of a disability) will usually not be put into an adult prison and instead get something more therapy oriented similar to juvenile detention.