I need advise on the following:

The device I am making will use this FET as an output. The device will
operate in the range 12 - 24 volts, depending on the users requirement to
illuminate a few light bulbs.

The FET I want to use can handle up to 16 amps at a max of 100v.

I want to suggest the recommended operating current not exceed 1 amp. as the
FET heats up considerably over 1 amp, and due to space restrictions a
heatsink is not possible.

At 24 volts that would be 24 watts, and at 12 volts that would be 12 watts.

How do I label this device so that a lay person will understand its maximum
operating capacity should not exceed 1 amp, depending on their selected
operating voltage?

Most lay users seem to look at wattage and assume that the indicated wattage
is for 12 or 24 volt operation.

Any suggestion appreciated.