I am so sorry that you are experiencing these problems with destructive behaviour with Luther. I am sure it is very upsetting for you. First of all rest assured that this is a very normal puppy and young dog behaviour. Puppies learn through oral exploration and it is part of our role as pet parents to help them learn limits. The behaviours will calm down with age. In general the goals will also be increased exercise and mental stimulation.
I would not attempt negative reinforcement such as striking Luther or speaking harshly as this will potentially create more serious behaviour issues such as anxiety and fear-aggression.
Try some calm corrections and positive reinforcement. If Luther destroys something, simply say in a calm voice "no" and stop interacting with him for a few moments. This over time will teach him that chewing is not a desired form of play. Also try reinforcing him as she starts to play in a good way by not chewing inappropriate things, and giver him a small training treat.
You can also try increasing her exercise and mental stimulation. These help with behaviour issues. Redirection to more appropriate activities or games will also help Other games which may be fun with Luther are hide and go seek either with you and another person, or you hide his toys and he has to find them. Or classic fetch.
I would also suggest a dog appeasing pheromone diffuser such as this one to help calm him;
www.drsfostersmith.com/product/prod_display.cfm?pcatid=32887
Here are some resources to help;
https://www.petcoach.co/article/6-tips-to-help-prevent-destructive-chewing/https://www.petcoach.co/article/10-ways-to-stimulate-your-dog-s-brain/https://www.petcoach.co/article/top-5-toys-gadgets-for-your-dog/https://www.petcoach.co/article/benefits-of-maintaining-an-active-lifestyle-for-your-pet/https://www.petcoach.co/article/6-common-myths-about-dog-aggression/I hope this was helpful!