@KirtiG48 if you have updateDateTime property in table and 3rd party is updating that value, then may be you can write job scheduler to fetch records updated within last 1 hr and additional filter criteria as per your requirement.
You can also try to write DB trigger before update which will store column value in another backup column for comparision.
You can use declare on change to monitor a specific property (Status property) in Pega and write activity to queue it to the queue processor with a delay of 1 hr inside the declare on-change rule. In the queue processor activity, you can write logic to send emails by checking the current status and the status while queuing are the same or not.
@KAMINENICHANDRAP Declare on change will work when I am changing the property value from Pega. Here the value is changing in database by some third party application. So declare on change will not work in this case.