Bl_power file gets created with value 1

How to change this so it gets created with value 0

Assuming you mean backlight power
Add an echo 0 in rc.local

Actually I got it back words by default it comes up 0 to turn off backlight I change it to 1
so I would do something like this in rc.local

this turns off backlight for lcd

echo 1 > /sys/devices/platform/rpi_backlight/backlight/rpi_backlight/bl_power

Yes. Something like rpi_backlight.bl_power=1 would probably work in cmdline.txt (check exact param)

FYI the above in the rc.local worked perfectly on reboot