People always say "bitcoin has a hard coded, guaranteed limit of 21 million coins".

However, I think the limit of 21 million is subject to the consensus of the users and miners?

So if a consensus is formed to allow more than 21 million Bitcoins to be generated, then it will be so, right?

Actually everything in Bitcoin can be changed, as long as there is the consensus for it.

So, there is actually no mathematical limit to the number of coins. It's just that the issuance of coins is not subject to a central authority, but requires a supermajority consensus.