Classes/Console/Core/Booting/RunLevel.php
public function getMaximumAvailableRunLevel(): string
    {
        if (!file_exists(PATH_site . 'typo3conf/PackageStates.php') || !file_exists(PATH_site . 'typo3conf/LocalConfiguration.php')) {
            return self::LEVEL_COMPILE;
        }

        return $this->error ? self::LEVEL_COMPILE : self::LEVEL_FULL;
    }
public function getMaximumAvailableRunLevel(): string
    {
        if (!file_exists(PATH_site . 'typo3conf/PackageStates.php') || !file_exists(PATH_site . 'typo3conf/LocalConfiguration.php')) {
            return self::LEVEL_COMPILE;
        }

        return $this->error ? self::LEVEL_COMPILE : self::LEVEL_FULL;
    }
Check if we have all mandatory files to assume we have a fully configured / installed TYPO3

@return string