I am travelling to Paris on the 7th of January, 2019. I wanted to know if the Christmas lights and decorations will still be there around the city at that time. It's my first visit to Paris, so that would be a great added attraction.
You can find here https://www.parisinfo.com/decouvrir-paris/les-grands-rendez-vous/noel-a-paris/illuminations-de-noel/les-illuminations-de-noel-a-paris locations and beginning/end date of Christmas decoration in Paris. Even though it's in French I believe it's still understandable.
Notice that most of them will end around your arrival. "Illuminations 2.0 sur le boulevard Haussmann" & "Les vitrines de Noël du Printemps Haussmann" (La Fayette) is the ones I will recommend.