Is it possible to delay a notification?

I’ve found this
https://documentation.onesignal.com/docs/sending-notifications#step-3-scheduling
but I would like the notifications of published articles of a certain category to be postponed in 90 days

Hello, sorry, we only support scheduling up to 30 days in advance.

You can add the onesignal_send_notification filter to include the “send_after” property and the date you want it to send (as long as within 30 days).
https://documentation.onesignal.com/docs/web-push-wordpress-faq#onesignal_send_notification-filter

Please contact [email protected] for further assistance or questions.

Hello,
is there no workaround to do it by modifying the plugin code in my installation?
Thank you for your reply
Enrico