Type that question into a search engine and you will mostly get pages selling a course. This one sells nothing: it describes the routes that exist, what they ask for, what they pay, and at what stage they open.
A warning first, because it saves time: there is no online income without regular work. What does exist are activities where the work you do today keeps paying tomorrow — and that is very different from passive income.
This guide starts from the case of a fashion content creator in Morocco, because that is what we know. The logic holds beyond it.