I need a wire color guide for my 2019 Equinox. I wanting in install a sub by pulling a signal from my speaker wires and running a line output converter but I need to know my speaker wire colors
You will need to pay for a day or two access to an online service manual. It's totally worth it as you can also download a ton of other useful info while there. I've used AllDataDIY and Mitchell1 before. I don't see 2019 listed on either for your vehicle. Mitchell1 can do a 2018 which may be correct - depends if it was a substantial change for the model year.
What i've done with the online subscriptions is to view the harnesses/instructions/schematics and then copy/paste into MS Word to make a useful document. I include all of the interior panel removal instructions to help with disassembly when running wiring.
Use your fader to verify if the rear speakers have a highpass filter or are attenuated (becoming more popular). You may find that the front door woofers have the best bass signal. Additionally, the rears may have some factory DSP on them to help them blend with the front - which won't work well with a sub in a different location.