I am 22 years old. Can my relatives apply for marriage immigration if they find someone who is willing to fake marriage with me abroad? What are the procedures?

Yes, there is no need for any formalities. Just get a marriage certificate. You apply for immigration on the grounds that you are interested in the nationality of that country. But fake marriage is illegal. If there is a conflict between you, you are not protected by law. You are legally married and will be bound by the marriage law. The so-called fake marriage is just in the name of marriage, taking some loopholes in the law and taking a shortcut, but it is also risky.