<?php
$pdo = new PDO(
    'mysql:host=localhost;dbname=alphpwcp_rvdb;charset=utf8mb4', // ①
    'alphpwcp_rvuser',
    'liquidfire22',
    [
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
        PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8mb4"       // ②
    ]
);