Postgres docker image entrypoint does not create extensions in other databases other than default

So this is the content of my /docker-entrypoint-initdb.d/initdb.sql script:

CREATE DATABASE mynewdatabase;
CREATE EXTENSION IF NOT EXISTS pgcrypto;
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

then I mount the volumes in docker:

  postgres:
    image: docker.io/bitnami/postgresql:11
    ports:
      - 5432:5432
    environment:
      - POSTGRES_PASSWORD=postgres
      - POSTGRESQL_USERNAME=postgres
    volumes:
      - ./db/create-db.sql:/docker-entrypoint-initdb.d/create-db.sql

The script is executed successfully, however the extensions are only accessible in the postgres default database

I have tried using something like:

CREATE EXTENSION IF NOT EXISTS "uuid-ossp" FROM/WITH;

But it did not work as expected