The 2023 UEFA NATIONS LEAGUE™ FINALS TICKETING TERMS AND CONDITIONS stipulate that all applicants must be aged 18 or over.
Moreover, applications submitted by or on behalf of people who have been banned from attending matches by a national association or any other authority will also be rejected. The same applies to people who are known to have threatened the security of matches in the past.
You can read the full 2023 UEFA NATIONS LEAGUE™ FINALS TICKETING TERMS AND CONDITIONS here.