Example code that shows how to change the date & time format for the Event Espresso 4 event editor date & time inputs

date_time_formats.php

<?php
//* Please do NOT include the opening php tag, except if you're starting with a blank file

function ee_change_dt_formats($formats) {
    return array(
        'date' => 'd.m.Y',
        'time' => 'H:i'
    );
}
add_filter(
    'FHEE__espresso_events_Pricing_Hooks___set_hooks_properties__date_format_strings',
    'ee_change_dt_formats'
);