I don't use a gray card because I shoot raw so I believe I won't need it (correct me if I am wrong).
You need a Color target.
If you really want accuracy you also need to calibrate your display, and have the target in each shot.
But if your lights are consistent, you only need to really make a target for the specific lens/camera/lights you are using. Note the WB from that target, and always set it to the same
And you can simply apply it, and it will be pretty good as long as you don't really mess with the colors.
You need a Color target.
If you really want accuracy you also need to calibrate your display, and have the target in each shot.
But if your lights are consistent, you only need to really make a target for the specific lens/camera/lights you are using. Note the WB from that target, and always set it to the same
And you can simply apply it, and it will be pretty good as long as you don't really mess with the colors.