creating docker-compose to handle multi arch

In the below code.I need linux/arm64 and linux/arm/v7 arch images. My understanding is docker-compose create with the platform option creates multi-arch images. But it not work as I expect.

version: '3'
services:
  app:
    build: .
    ports:
      - '4000:3000'
    platform: linux/arm64
    platform: linux/arm/v7

Thanks.