No. Realme X does not have the notification light but it does have the Always-On display - so you can get notifications via it.
No. Realme X does not have the memory card slot but you should not worry about it because it comes with 128GB internal storage option, which is pretty big from a regular usage perspective. Besides, the mobile also has OTG support.
Yes, Realme X does support fortnight.
Yes, Realme X does have a 3.5 mm headphone jack.