You can download a copy of Google data about yourself by going to Google Takeout

You can download a copy of all the data that Google has collected from your account by going to Google Takeout.
https://takeout.google.com/

Data collected from all Google products are listed on the Google Takeout. You can choose to download all or selective product data that you wish to download or backup.

You can control and monitor what data Google collects about yourself by going to the My Activity.
https://myactivity.google.com/