How do you derive Charles law?
And an empirical law derives from observation and experiment.
And what was the OBSERVED experimental result?
Given constant temperature, and constant amount of gas.....the volume occupied by a gas is proportional to its absolute temperature.
Many of these gas laws were formulated in the great age of steam in the 18th and 19th centuries, when the performance of pistons in locomotives, and steamships were studied and perfected.