Yep, I layer frags with essential oils regularly.
Most of my favourite scents are patchouli based, so I layer them with patchouli oil to enforce the scent. Sometimes ,for special occasions, I use oud oil to add this wonderful note to them.
Cause I don`t prefer intrusive sweet or floral scents I`ve got no experience in layering with the suitable oils.
This practice is a great deal to boost and/or change the quality of a scent.
Go on, be creative, make your experience!