Preheat oven to 350°F. Butter three 8-in. round cake pans; line bottoms with parchment. Set aside. Sift baking powder, cinnamon, and 4 cups of the flour in a bowl; whisk in salt. Set aside. Whisk whipping cream and sour cream in a measuring cup; set aside.
Beat sugar, butter, coconut oil, and lemon zest in a stand mixer fitted with a paddle attachment on medium-high speed until fluffy, 3 to 4 minutes. Add eggs 1 at a time, beating until combined after each addition. Beat in vanilla and almond extract, if using. Reduce mixer speed to medium-low; beat in flour mixture in 3 additions, alternating with 3 additions of whipping-cream mixture, beginning and ending with flour, beating until just combined after each addition.
Toss together blueberries and remaining 1 Tbs. flour in a bowl, and fold into batter. Pour batter evenly into prepared pans.
Bake until tops of the layers start to brown and a wooden pick inserted into centers comes out with a few crumbs, 30 to 35 minutes. Let cool 10 minutes. Remove layers from pans, and transfer to a wire rack. Let cool completely, about 1 hour.
Place blueberries and water in a saucepan; cook over medium, stirring and mashing occasionally with a rubber spatula, until blueberries release juices, 8 to 10 minutes. Pour through a mesh strainer into a bowl, mashing blueberries with a spatula to release juices. Discard solids. Set aside 3 Tbs. juice.
Beat butter and cream cheese in a stand mixer fitted with a paddle attachment on medium speed until creamy, about 1 minute. Gradually add confectioners' sugar, beating until combined, 2 to 3 minutes. Add vanilla, salt, 3 Tbs. blueberry juice, and 2 Tbs. whipping cream; beat until incorporated, adding remaining 1 Tbs. cream, 1 tsp. at a time, as needed until smooth and fluffy. Beat mixture until creamy, 2 to 3 minutes.
Using a serrated knife, trim domed tops of the cake layers to make flat. Place 1 layer on a platter; spread top evenly with some of the frosting. Top with second layer; spread top evenly with some of the frosting. Top with remaining layer; spread top and sides of cake with remaining frosting. Decorate with marzipan stickers and/or mini gold stars, if using.