A Grande (16 fl oz) Starbucks Cold Brew carries 205 mg of caffeine - 142 mg more than a single shot of Espresso (1 fl oz, 63 mg). But size explains most of that gap: per fluid ounce, Espresso is far more concentrated at 63.0 mg/oz, against 12.0 mg/oz for Starbucks Cold Brew.

Figures are each brand's own published nutrition data; see the source link in the table below. Add either one to the caffeine calculator to see how it fits your personal daily limit.

Standard serving, side by side

Starbucks Cold Brew, Grande, 16 fl oz (473 ml) 205 mg
Espresso, Single shot, 1 fl oz (30 ml) 63 mg

Sources

Drink Serving Caffeine Source
Starbucks Cold Brew Grande, 16 fl oz (473 ml) 205 mg Starbucks published nutritionSource
Espresso Single shot, 1 fl oz (30 ml) 63 mg USDA FoodData Central, espresso, restaurant-preparedSource

Only the standard serving of each drink is shown above; see each drink's own page for every size.