Become an Influencer
I don't know if you have heard or not but the influence marketing industry has reached $16.4 B by the year 2022 and is continuously increasing. Brands spend more than $100 per influencer-Generated Content.
Becoming an influence is not so difficult you just need a mobile or laptop & Good Internet Connection.
KDP Business model
This is the One Time effort working business model with the expectation of unlimited earnings.
In this business model you have to create an e-book and publish it to amazon kindle, and when the sale goes on you will get paid a royalty for that. This business can give you money while sleeping because Amazon is a 24*7*365 working business site with a global network connection.
If you have a good book-creating idea then you just create your E-Book and upload it on Amazon KDP and get a royalty every month with the same book
Affiliate Marketing
It is also an easy way to earn passive money without doing anything. You can affiliate marketing with your website if you have or you can do it through social media platforms like Facebook Instagram, Twitter, Telegram, and even WhatsApp also. You just need traffic. You can refer to amazon's product offer and get paid, I also come to know that in software their commission rate is higher than. It gives commissions starting from $100 to $10,000/ per sale.
Blogging
POD
BONUS
Invest In Stock, May you can think investing in stock are risky but a long time is always profitable there is very risky in the long term game. If you don't have any knowledge about the stock market then I personally suggest you learn at least as little as you can.