What kind of process have to go through? Who make the final votes? I guess the change is similar to implementing BIP.
I heard many posts here said "Economic Majority" vote decides. Does this mean who hold the most bitcoins decide? Maybe not. I guess BIP is determined by Bitcoin Core developers, so the total bitcoin supply (21 million) is also determined by Bitcoin Core developers.
Also, the argument against the "Economic Majority" is it is often the case we can't find holder for the addresses with a lot of bitcoins. How can we contact them for vote?
Thank you indeed!
Call Blockstream , tell them you are a new bank, offer them a few million bucks and your request will be soft forked in within a year or two.
Hey, it how segwit and LN got shoved down bitcoin users throats when no one wanted it.

Results vary by how much fiat you throw at them.

FYI:
On a more serious note, it is nothing more than a number coded into the software.
Change the number in the code is all that is required,
oh that all of the other nodes need to upgrade to your new code for it actually to change it for everyone.