First thing first.
On landing you can't go below what the chart published.
Go below you have to be approved cat II or cat III and still need the chart.
Now on take off
Standard is 3-4 engine 1/2 mile or 2400 rvr
1-2 engine is 1 mile or 5000 rvr.
Now if you want go lower you look at your ops spec.
Take a look at 9A in KAPA you will see that you can lower than standard
But for sure you can't go 500 rvr because there is not an rvr report