How to handle time zones in complicated queries?

I have the following code... that will essentially tell me how many many behaviors happened for a given day, but will also return 0s for days where no behaviors are stored. My question is two-fold:

(1) This was some of my earlier code and so I am thinking about cleaning this up, refactoring ~ are there any design patterns that I should use here? Or is this fine?

(2) All dates are stored in UTC, so I need to change the query to account for time zone. Otherwise the charts will show behaviors on the UTC dates, and not the local dates. So I was thinking I could just modify the following part: b.created_at < d.generated_date + INTERVAL 1 DAY AND to account for the diff between their local time and utc? Is there a cleaner better way to think about this?

Thanks in advance.

    protected function getBehaviors(Child $child, int $daysBack, $operator = '>=', $typeID = null)
    {
        $typeWhere = ($typeID) ? 'b.behavior_type_id = ' . $typeID  . ' AND': '';

        return DB::select($this->getRecursiveDatesQuery() . "
            LEFT JOIN behaviors b
                 ON b.child_id = :child_id AND
                    b.created_at >= d.generated_date AND
                    " . $typeWhere . "
                    b.created_at < d.generated_date + INTERVAL 1 DAY AND
                    b.value " . $operator . " 0
            GROUP BY
                d.generated_date
            ORDER BY
                d.generated_date ASC
        ", ['child_id' => $child->id, 'days' => ($daysBack - 1)]);
    }

    private function getRecursiveDatesQuery()
    {
        return "WITH RECURSIVE dates as (
                    SELECT
                      CURDATE() as generated_date,
                      1 as days
                    UNION ALL
                    SELECT
                      generated_date - interval 1 day,
                      days + 1
                    FROM
                      dates
                    WHERE
                      days <= :days
                )
                SELECT
                    DATE_FORMAT(d.generated_date, '%m/%d') as created_day,
                    COALESCE(COUNT(b.id), 0) as total
                FROM
                    dates d";
    }