RSS feed : a way to limit to the events in the next x days ?

Hi !

For a specific use, I need to cap items that are in my feeds.

I was able to set a limit to my (past) posts feeds to the “last 15 days” with the following code:

add_action( 'pre_get_posts', function( $q )
{
    if(    $q->is_feed() 
        && filter_input( INPUT_GET, 'wpse_previous_2_weeks', FILTER_SANITIZE_NUMBER_INT ) 
    )
        $q->set( 'date_query', 
            [
                [ 
                    'after'     => '15 days ago',
                ]
            ] 
        );

I would like to add something that would act similarly to cap listed event in the RSS feed to the ones in the “next X days”.

Anyone has an idea on how to proceed for this (ideally though a similar approach than for the posts, otherwise it could be by doing some changes in the RSS template file)

Note: the current “full events” RSS feed is already used by some existing consumers – I need to keep it running.

Thanks for any idea !
Matt