Hi Aion,
First step, send off the reply
Next, create a Delay step and set it to 5 seconds

Now when you run Get emails (V3), exchange should have had plenty of time to send the email
Note: The more reliable search terms you use, the more accurate your result will be. This is important if your inbox might send a lot of emails in quick succession

Get emails (V3) will always give you an array, even if you set the result "Top" to 1.
I would recommend running through your results through a loop of filter to return the first email that matches the expected Conversation ID
(This process also works with the Outlook connector in PowerApps)