Yes. Although providing leave under the ARPA expansion is purely voluntary, this is not akin to a benefit that employers can fully choose to provide only to certain employees. The law now imposes nondiscrimination rules, so employers may not discriminate in offering leave in favor of highly compensated or full-time employees or based on tenure.
It appears that the non-discrimination test applies separately to EPSL and EFMLA. So, for example, being disqualified from taking the tax credit for EFMLA leave (due to it being provided in a discriminatory manner) may not disqualify the employer from taking the tax credit for EPSL (as long as it was provided in a non-discriminatory manner).