Auxiliary Lights?

Depends a little on the power draw from your new lights and the rating of the circuit you want to tap into.

For a low power device I have got some of the Triumph connectors and made an insert that goes between the tail light (always on with ignition) and my device on the basis I can quickly swap back to factory standard by removing it should I sell. If there is spare amps on the circuit I’ll power my device direct.

If the power demand from the device is high then I do the same but use the low power splice to only switch a relay. The relay high power side is directly connected to the battery and switches to the high amp device (e.g Sound Bomb horn).

Don’t forget to fuse everything and use the right rated wires for your application.

Definitely connect to power switched by the ignition or you will one day forget to turn the lights off and flatten your battery (or forget to turn them on).