Hello,
In Outlook for Android, the method to report phishing or junk mail should be done before the message is moved to the Junk folder.
Long-press the email subject to select it, then tap the three vertical dots in the upper-right corner. You will find options to report phishing or junk mail there, so you do not need to open the email itself.
For any other requests, please tap your account, go to Settings > Help & Feedback > Send Feedback, and submit your feedback to the developers.