For this type of free airdrop you can follow the NFT airdrop from the Solana platform. Now a lot of free airdrops are going on every day on the Soul platforms. All you have to do is create an account on sollet.io or another supported web wallet, keep a small amount of sol (probably 2/3 $ sol) to claim the transaction. You can then claim a free airdrop whenever they make an announcement.
means it is not free because it requires SOL capital to be able to follow it.
some free ones only give the task of sharing the link on social media. and they can get the airdrop token. although most of these airdrops won't make any money.
indeed an airdrop event that sometimes requires a small capital can be successful and indeed make us money. but still, be careful to choose an airdrop project.