WordPress at a glance
function is not described

update_site_meta() WP 5.1.0

Updates metadata for a site.

Use the $prev_value parameter to differentiate between meta fields with the same key and site ID.

If the meta field for the site does not exist, it will be added.

No Hooks.

Return

Int/true/false. Meta ID if the key didn't exist, true on successful update, false on failure or if the value passed to the function is the same as the one that is already in the database.

Usage

update_site_meta( $site_id, $meta_key, $meta_value, $prev_value );
$site_id(int) (required)
Site ID.
$meta_key(string) (required)
Metadata key.
$meta_value(mixed) (required)
Metadata value. Must be serializable if non-scalar.
$prev_value(mixed)
Previous value to check before updating. If specified, only update existing metadata entries with this value. Otherwise, update all entries.
Default: ''

Changelog

Since 5.1.0 Introduced.

Code of update_site_meta() WP 5.5.2

<?php
function update_site_meta( $site_id, $meta_key, $meta_value, $prev_value = '' ) {
	return update_metadata( 'blog', $site_id, $meta_key, $meta_value, $prev_value );
}