The presidential election is decided entirely by electoral votes, and once those are cast then that’s that. You cannot just change it to ranked choice unless you change the constitution itself

However, states are free to decide how they want to allot their electoral votes. Considering it is a state-by-state contest by nature, only that interpretation is even feasible. Technically you could do it if every state decided on the same system of RCV, but I highly doubt you could get every state to effectively make it a popular vote decision, considering most states already don’t like that idea.