Антон Р.

foreach ($priceSize as $value) {
                    foreach ($sizesObject as $size) {
                        if($value['id'] == $size['id']) {
                            $price = new Price();
                            $price->store(['price' => $value['value'],'product_id' => $product->id]);
                            $price->entity()->associate($size)->save();
                        }
                    }
                }