Mark Specific Users as Online Always

yzc_mark_users_as_online.php

<?php

/**
 * Mark Specific Users as Online Always In The User Profile Page.
 */
function yzc_mark_users_as_online( $is_online, $user_id ) {

    // List of Always Online Users.
    $online_users_ids = array( 1, 2, 3 );

    if ( in_array( $user_id, $online_users_ids ) ) {
        return true;
    }

    return $is_online;
}

add_filter( 'yz_is_user_online', 'yzc_mark_users_as_online', 10, 2 );

/**
 * Mark as Online in Members Directory.
 */
function yzc_mark_users_as_online_in_members_directory( $classes ) {

    global $members_template;

    $user_id = $members_template->member->id;

    // List of Always Online Users.
    $online_users_ids = array( 1, 2, 3 );

    if ( in_array( $user_id, $online_users_ids ) ) {
        $classes[] = 'is-online';
    }

    return $classes;
}

add_filter( 'bp_get_member_class', 'yzc_mark_users_as_online_in_members_directory' );