This might be an unpopular opinion but as someone who has tried protein powders, shakes and all kinds of additions, it's just not worth it. Flavored creamer is 30-35 calories for a tablespoon. Coffee is a joy, don't take that away from yourself. Cut somewhere else, this ain't it.
You can try sugar free syrups or creamers, spice blends like cinnamon and cardamom as others have suggested, or flavored coffee beans. Creamer won't have much protein to speak of unless you're using a dense protein shake, at that point it will just taste worse and you'll rob yourself of that little joy.
You may have to make the same mistakes I've made, hell maybe you'll enjoy protein shakes in your coffee. But what it came down to for me was, I wasn't finishing it because it was disgusting. A tbsp of oatmilk creamer "the oatmeal cookie one" with a nice coffee roast is bomb, and brings the delight and the go (and the go!) that I needed to start my day right. I use an Aeropress, it makes for a great and rapid brew, far better than drip for me, and less cleanup.
Congratulations on your commitment to fitness, it all starts with little thoughtful changes like this one. Best of luck, stranger!