Mix strawberry-flavored gelatin mix, sugar, and boiling water together in a large bowl, stirring until gelatin and sugar have dissolved.

Refrigerate gelatin mixture until it begins to turn thick and syrupy, about 10 minutes.

Gently fold frozen whipped topping into gelatin mixture until thoroughly combined.

Fold the 2 1/2 cups of sliced strawberries into whipped topping mixture.

Spoon filling into graham cracker crust and decorate edge of filling with 8 strawberry halves.

Refrigerate at least 2 hours before serving.