Preheat oven to 350°F. Mix pretzels, butter, and 3 tablespoons sugar until combined; press firmly into bottom of 9x13-inch dish.
Bake crust 10 minutes; cool completely on wire rack.
Beat cream cheese and 1 cup sugar in large bowl with electric mixer about 2-3 minutes until light and fluffy.
Gently fold in whipped topping until smooth and combined; spread carefully over cooled crust, sealing to edges.
Refrigerate while preparing strawberry layer.
Stir both Jello packages into 2 cups boiling water for 2 minutes until completely dissolved; add 1 cup cold water.
Stir in thawed strawberries and juices; refrigerate about 20-30 minutes until egg-white consistency, not fully set.
Carefully pour over cream cheese; spread gently to cover completely.
Cover; refrigerate at least 4 hours or overnight until Jello is completely firm before cutting squares and serving.