Use buildx build linux/arm64 in docker-compose file


I can build my dockerfile separately using following command:

docker buildx build --platform linux/arm64 -t testbuild .

now I want to use buildx in docker-compose file but how and how to say I want to use the arm64 architecture? This is the structure when I use the normal build.

build: …/testbuild
image: testbuild

Does anybody know?