172 driver:
I have personally never seen that written in any AIP. In one I could find the range of the associated Lctr. but not the localizer. I was taught 18 nm (ICAO) and use that in my practical flying (18 nm, correct sensing, arm VOR/LOC).
I have also seen the LAX localizer for 25L/R, which extends some 45 nm to the east?
More like 50 miles with the four ILSes from the east. That is called extended service volume (ESV) and requires more frequency protection and good localizer transmitters. You don't see ESV mentioned in any AIP, either.
In your practical flying if you use the localizer only where it is authorized on the approach chart, you then couldn't care less about that 18 miles.