As Kelly has mentioned Ezoic will detect when an account meets the necessary criteria for the next Level and automatically transition their account into the Level which has been achieved. The site needs to have at least one month fulfilling the minimum Level requirements.
You can read more on this here - https://levels.ezoic.com/faq/
Increasing in Levels takes into account Visits and Revenue for the previous month.And if that has been achieved in the previous month it can take time for this to update in the system and for the team to assign the correct Level when they have reviewed the account.
Sites can also apply early in their dashboard if they believe they are eligible or have additional circumstances that would make them eligible for a level upgrade. This option would show in your Levels dashboard as a button for you to apply to Next Level.