No. Children and teens are not to smoke or be able to buy tobacco products (cigarettes, shisha/ hooka, cigars, chewing tobacco, e-cigarettes, etc.). Not even for/on behalf of adults. Furthermore, minors must not be allowed in so-called "smoking bars" (bars inside which people can freely smoke). The restriction is grounded on the Youth Protection Act, which principally differentiates between children (up to 14 years) and teens (14-18 years) -i.e. minors- and adults (18 years and over).
Children and Youth Protection
How does the German law protect children and teens?

Children (up to 14 years) and adolescents (14-18 years) need appropriate protection- that is why they are subject to specific regulations. Not only are children and adolescents prohibited from the consumption of alcohol and tobacco or going to bars and clubs, but the law also regulates the consumption of films and video games by minors. You can find details of such protective measures in the Youth Protection Act.
What is allowed (or NOT) for children according to the law?
Important
If your child smokes, drinks alcohol, or does things they are not old enough to do, try to speak openly with them. Stay calm and matter-of-fact: Tell them about the numerous negative consequences (addiction, illness, etc.) that their behaviour may cause. You can find help at many Family & Parenting Advice centres or the Youth Migration Service (JMD). You can learn more in our chapter "Parenting".