WP_Query Limit Data_Query last 90 days

In order to query posts with a date_query, you can pass the argument of column post_date_gmt which is the date the post was published, and then pass the argument of before/after and a string to represent your request. So for published posts from now until 90 days ago, you would put this in your WP_Query args:

'date_query' => array(
        array(
            'column' => 'post_date_gmt',
            'after'  => '90 days ago',
        )
)

This says get me all posts from 90 days ago and AFTER, which would stop at present time.

You could pass the string 3 months ago, 1 year ago, etc. It basically takes on the same behavior of strtotime().