Disclaimer: this is my first PI project, and at the moment I have only a basic knowledge of circuitry, so please be gentle.
I'm looking to construct a device using a PI 3B+ that'll be housed outdoors in a sealed project box. As part of this, I'd like to have 6 weatherproof LEDs on the box to show status, and the only ones I can find are 12v 15mA. I know that this is too much for the GPIOs to handle directly, so I need another solution - preferably one that doesn't involve me having to provide a separate power supply.
At the moment I'm leaning towards a relay hat on the PI with a USB to 12v adapter providing the power to relay to the LEDs. Before I go out and buy the parts, am I working in the right direction, or is there a better way? Also, given that the LEDs are 15mA and the adapter output is 0.6A, do I need to put a resistor between the relay and each LED?