It's a development stage designed to separate parents and their babies since time began, but isnt 24/7.
Stay in contact always. Don't get into routine of being in separate rooms all the time. There is no reason for teens to stay in their room and it's not that usual nowadays. Be fair about TV and gaming in communal areas.
Try best to be always reasonable and just. They are very fond of fairness. Explain your reasons like a judge. But don't be emotionless like a judge. Care. Deeply.
Be interested in what they are interested in, without cynicism. Eg veganism, environmental concerns, rock metal, blue hair etc. Notice changes they've done to their appearance and compliment them. Teens are very very insecure even the confident ones.
Keep dialogue open. Be clear when they hurt you. They are still human and don't want to hurt their mum really. It'll soften them if your not always so professionally parenting and show your human side.
Remember they're still children. Set and enforce boundaries but don't be silly strict. Allow freedom but be there (if like a 3 year old trying slide at park) it's too much and they need you. Don't ever say no to being there/ picking them up, and don't judge. Try not to throw it in their face that they were "all grown up/ you knew nothing etc" 3 hours ago. Be there for them unconditionally.
Kids respond v well to ridiculous totalitarian rules in secondary schools so are capable of conforming. If they see it fairly applied. Teach them to question this but not so much that they end up in isolation. Be kind if they do. Schools are harsh.
It's not all the time. They still love you.