Low power compact current limiting
The smallest package is the 6 Lead On-Semi SC−70 2x2mm, or 2x2mm TSOT−23 with their CAT4003B.
2.4-5.5Vin
(20mA at power on)
The CAT4003B has 3 drivers each with a single enable/dim pin.
CAT4003B  3 drivers   2x2mm=4mm², 3 of these would take up 12mm²

On-Semi CAT4003B Datasheet

On-Semi's CAT4004A an eight pin 2x2mm has four channels and a Rset pin to set the power on current.  LEDs can be adjusted between 2mA to 40mA with 1.3v logic level signal.
LED Current for all 4 channels set by External Resistor and dimming with a single Enable/dim pin.

On-Semi CAT4004A Datasheet

You could drive the 3 colors in series with the Microchip CL320,  3 drivers 3 dim pins 4.9x3.9mm=19mm²  4-15v Three currents 20mA, 25mA, and 30mA.

Microchip CL320/325/330 Datasheet
On-Semi CAT4003B Datasheet