you can add vanilla flavor by making a semi-homemade recipe using a store bought vanilla ingredient. Vanilla pudding, ice cream, creamer, yogurt, milk, syrup (the ones you add to coffee), protein mix, ...
For those moments, I know that I can elevate my DIY iced coffee any ... your choice of milk or coffee creamer and sweetener, if desired. I'm personally a fan of vanilla iced coffee with oat ...