You can try below code to change local date to UTC date.

<?php
namespace MagemonkeyUtcDateModel;

use MagentoFrameworkStdlibDateTimeTimezoneLocalizedDateToUtcConverterInterface;

class UtcDate
{
    /**
     * @var LocalizedDateToUtcConverterInterface
     */
    private $localtoutc;

    public function __construct(
        LocalizedDateToUtcConverterInterface $localtoutc
    ) {
        $this->localtoutc = $localtoutc;
    }

    /**
     * convert UTC Date
     *
     * @return string
     */
    public function convertUTCdate(): string
    {
        $localDate = date('m-d-Y');
        return $this->localtoutc->convertLocalizedDateToUtc($localDate);
    }
}