If you are using the date_sunrise and date_sunset functions in PHP, you can specify the zenith angle to get sunrise and sunset times. The zenith angle represents the angle between the sun and a line perpendicular to the Earth's surface. The values you mentioned, date.sunrise_zenith and date.sunset_zenith, are not directly available in PHP, but you can achieve similar results by specifying the zenith angle in the date_sunrise and date_sunset functions.

Here's an example using these functions with a custom zenith angle:

<?php

// Replace these values with the latitude and longitude of your desired location
$latitude = 37.7749;
$longitude = -122.4194;

// Specify the custom zenith angle for sunrise and sunset
$zenith = 90.83; // Civil twilight

// Get sunrise and sunset times as timestamps
$sunriseTimestamp = date_sunrise(time(), SUNFUNCS_RET_TIMESTAMP, $latitude, $longitude, 90.5, $zenith);
$sunsetTimestamp = date_sunset(time(), SUNFUNCS_RET_TIMESTAMP, $latitude, $longitude, 90.5, $zenith);

// Set your desired timezone
$timezone = new DateTimeZone('America/New_York'); // Replace with your timezone

// Create DateTime objects with the specified timezone
$sunriseDateTime = new DateTime("@$sunriseTimestamp");
$sunriseDateTime->setTimezone($timezone);

$sunsetDateTime = new DateTime("@$sunsetTimestamp");
$sunsetDateTime->setTimezone($timezone);

// Format times in AM/PM format
$sunriseFormatted = $sunriseDateTime->format('h:i A');
$sunsetFormatted = $sunsetDateTime->format('h:i A');

// Output the times
echo "Sunrise: $sunriseFormatted" . PHP_EOL;
echo "Sunset: $sunsetFormatted" . PHP_EOL;
?>

Make sure to replace 'America/New_York' with your actual timezone. This should provide you with accurate sunrise and sunset times in your local time.

In this example, the $zenith variable is set to 90.83, which corresponds to the civil twilight. You can adjust this value to get sunrise and sunset times based on different twilight phases or other zenith angles.

In this example, the format('h:i A') method is used to format the times in the desired format with AM/PM indication. Adjust the format string as needed for your specific requirements.

Keep in mind that the date_sunrise and date_sunset functions use the system's timezone settings, so make sure your server's timezone is correctly configured. Additionally, these functions may not be available if the "date" extension is not enabled in your PHP configuration.