Hello Praseena,
You can try to use API to get test result attachment. Please refer to this document Attachments – Get Test Result Attachment Zip, and use parameter runId
then download a test result attachment by using (for example) https://{instance}/{collection}/{project}/_apis/test/Runs/{runId}/Results/{testCaseResultId}/attachments/{attachmentId}?api-version=5.0-preview.1
Besides, it’s not possible to automate this process, you may need to download the attachments manually.
Best Regards,
Tianyu