Keep it the same like Dad911 said. We like Mapei products such as this
https://www.lowes.com/pd/MAPEI-Keracaulk-S-10-5-oz-Charcoal-Sanded-Paintable-Latex-Caulk/1000063685
1/16 grout joint will need a none sanded grout so you need to buy the caulk to match. Most brands will have have both sand and non sanded caulking with exact grout color match.