Changing the font size requires custom layouts (as per https://stackoverflow.com/questions/24320601/how-to-style-notification-message-for-pushnotification ), however custom layouts are only supported from Android 7 (sdk 24) which is a no-no for Aedict (because of #741 ). So I can only change the notification title and text as you suggest.
Regarding the navigation: historically, Aedict opened the search screen when clicking the notification. I'd like to preserve that for backwards compatibility. I'll thus add a setting for this - checking this option will cause Aedict to open the word of the day instead of the search screen.