So there are 21 million total because that is how it was coded. Will it be possible to increase the supply or even make it infinite if someone was able to crack the code?
Supply is know to all how can it be manipulated again! That is no longer possible except that will mean that Satoshi Nakamoto has come back to temper with the Supply, I don't think any other devs can do anything with the Supply,
Bitcoin total supply will always remain 21 million and nothing more.
No, even Satoshi has no power to tamper the supply of Bitcoin. It is all about the consensus of miners. Satoshi had been long gone on the scene and even if he come back, I don't think he has that great influence to affect miners into agreeing to anything he wanted to do with Bitcoin development. And if he do, he will more likely create a Bitcoin fork and that is not Bitcoin itself.