What if you microwave the earl gray in say 50ml of water, then let it cool, and add to cococolo.
Brewing the tea in hot water would release other flavours you won't get when you cold-brew.
Good question: I'm going to try it. A tea bag could release microplastics, so I'm using tea leaves.
Edit: Need 75 ml of water to get 50 ml tea because the leaves absorb water.
Edit 2: The result was bitter. Cold brew tasted better. Perhaps the point is not the taste of tea but the bergamot oil in Earl Grey.