Re: Retrieve only e-mails from a specific domain form the inbox
Using a schedule to check the Inbox of a mailbox every 30 minutes will be a very inefficient way to execute the flow and a wasteful use web of resources when Microsoft offers a ready-made trigger to do what you need. This trigger is constantly "listening" to all incoming emails. Remember that your use of Power Automate is also not unlimited (see Requests limits and allocations).
A single trigger will be more efficient else you will creating multiple flow steps or even duplicate flows - and that means there are more part to manage and fix should things go wrong.
There are a number of different ways to achieve your desired outcome, here are three possible options: Filter using the From email address:

or use a condition to check the From address:

or use a trigger condition to check the senders email domain name:

Or a combination of the above.
The key point is to start with the trigger When a new email arrives, then build a working flow that you can understand. Start simple and don't worry too much about all the different ways of something. You can later refine and improve your flow as you discover new issues, efficiencies or if your requirements change.
Ellis