Do buck converters/voltage regulators change max amperage?
There are several different things that can limit the maximum output current of a buck converter, and of course the lowest sets the overall limit. Different configurations or ambient temperatures may change which limit wins, so it's not always easy to translate specifications for one configuration into another.

The output power can't be greater than the input power, and in fact 90% or so of the input power, depending on the efficiency. If the input power is limited, it will limit your output.

The inductor has two limits on its maximum current, thermal from \$I^2 R\$ losses (which will depend on ambient temperature), and magnetic saturation.

The input switch will have a limit on maximum current. It will have a thermal rating, and it may have a programmed upper limit set by the controller for protection.