How to expand doppler env vars with a local env var value

Supposedly I have a local env var (already defined before I run infisical) POSTGRES_URL="postgres://myusername:mypassword@localhost:5432/mydatabasename"

I want to have in the cloud env vars one which is defined as follows
DATABASE_URL=${POSTGRES_URL}

But it says that env var POSTGRES_URL value is not defined.

How to make that cloud env vars can be expanded by a local value? The use case is that some of the env vars are defined by the cloud platform (i.e.) and I don’t know them before hand.