You just respectfully decline allowing yourself to be a part of it. That’s all you can do.
You tell them that is not something you’re interested in participating in, explain to them why you do not want to participate and it with them (should you feel that will help in adding clarity to this situation), and then you live your life.
We do not have to live the life that people want us to live. I know it may feel like that at times and people really can be assertive, but you don’t have to. That’s the difference between living your life and living a life.