How to use Global Variable in Cloud Flow in Power Apps

How to define base URL, client ID and client secret only once and then use it in cloud flows?

Is it possible to save these details in another table and read it from that table dynamically inside cloud flow?

or

Is there a way to create global variables that we can use inside cloud flow?

Cloud flow that I'm using

You can achieve this by creating a Solution for your automation. A Solution in power automate allows you to group components of an automation such as flows, connection references, and what you need environment variables.

On the left panel in power automate select solutions -> new solution -> and fill out the information to your preferences:

Once you have your solution created, you can add all the necessary components you need that your exisiting flow(s) use:

You can also create environment variables, which are essentially global variables for your environment where you can define static values to be used across your flows. They can be accessed in the dynamic content when editing your flow.