It could be Airdrops etc.
Airdrops or bounty campaign is not passive income.
Passive income is money that you don't have to actively work for; it comes in from something that already exists and continues to work for you.Through my years in the CryptoSpace, I've found platforms often organise events to let users earn passive income through risk averse and conservative means.
Please share us some of those platforms because in all my years there is no such thing called safe and risk free crypto investment and if they do then 99% of the time they will just scam you. Well there are some like staking but the returns is not worth the risks we are taking so just better hold instead of giving your assets to any custodial services that promises to give x% of returns.