built in charge controllers take amps they need?
Not true.

You're mixing up the specification of a charge controller with that of a battery.

Each battery type has a 'preferred' way of getting charged - constant current, constant voltage, or (often) a mix of those over time.

A charge controller is connected to a power source (most often constant voltage, like USB 5v or mains, but I guess constant current or a mix, like for solar power is possible too) and outputs whatever voltage/current 'pattern' the battery requires for most optimal charging given the user requirements/settings (fast, slow, trickle...).

The reason most batteries will have a maximum charge power rating is simply to prevent excess heat from building up.

To make things more complicated, modern batteries often have a built-in charge controller - mostly to prevent mishandling from causing fires...