Yes, it is possible to request to join a match even if your level is not within the required span.
When you open the match detail screen for a match outside your level range, you will see a "Request to Join" button. Tapping this sends a request to the lead booker of the match.
The lead booker will then review your request and choose to either accept or decline it. If your request is accepted, you will receive a notification and will be able to join the match as normal.