This feature was announced earlier in May and now it has been roll out. Google now lets you auto delete your location history web activity.
Currently, you can go in and manually delete your activity data at any time. Going forward, you can instruct Google to auto-delete your data every 3 months or every 18 months — or continue to delete it yourself whenever you wish.
This includes location history and activity data, such as online searches, places you have visited, and content you have viewed on Google-owned apps.
Any data older than 18 months will be deleted as well if you choose to have an auto-delete feature turned on.
The feature is rolling out over the next few weeks globally on both Android and iOS.