If you want to rotate the pages in the PDF on your mobile app. you need to access Organize Pages feature in Acrobat Reader app. however you will require subscription for that.
As noted for the mobile app one would need to purchase the feature for the app.
Reader on a computer can rotate all the pages in a PDF in increments of 90 degrees but cannot save the changes.
Acrobat Professional or Standard can rotate individual pages and save the results.