Set default machine memory for apps during creation

I’m currently using the Fly GraphQL API to create apps for our pull request preview environments.
Unfortunately, our apps crash because the memory exceeds the default machine memory of 256 Mb. Is there a way to increase the default machine memory to 512 Mb during app creation or after? Or can it be done using the Fly Launch configuration file?
The equivalent of flyctl scale memory 512 -a xxx.