Google has now made the feature available more or less universally available. Another article on the same topic is at https://www.forbes.com/sites/daveywinder/2019/05/05/google-confirms-it-will-automatically-delete-your-data-what-you-need-to-know/amp/
It’s not surprising that data from your “Web & App Activity” reveals information about what you’ve been up to, whether it pertains to your location or not. For example, if I log into my Google account and check out my history in this field, I see data points about areas in Manhattan I’ve viewed on Google Maps on my phone, searches I’ve done in Gmail and Google Maps, and articles I’ve read on Google News.
To explore this data, manually switch on or off tracking in fields like these, and to look for that new auto-delete feature, start by signing into your Google account on a web browser on either a desktop or mobile device. Once you’re in your Google account, look for a field called “Data & personalization.” There, you’ll find those “Web & App Activity” and “Location History” fields. When the choice is available, you should see an option to automatically delete this data, and you can then opt for how often you’d like that to happen.
In the meantime, if you’re creeped out by all this, you can choose to “pause” the collection of the information. If you do that in Location History, for example, you’ll see a warning that pausing it “may limit or disable personalized experiences across Google services.” Opting into auto-delete is a good idea when it’s available.
While issues of privacy and location are on your mind, it can’t hurt to check out what kind of location permission you’re giving to your apps, after you’ve explored your Google Account settings through a browser.
On an iPhone, go to Settings, then Privacy, then Location Services. Conveniently, Apple gives iOS users the option to choose between Never, Always, and While Using the App—the last choice is a good compromise. (Thus, it’s nice that you can set Uber to “While Using.”) Do you dislike that Google Maps can figure out where you are? You can choose “Never” as an option for that app, but then when you fire up Google Maps, you’ll notice that it can’t localize you. (Which means that searching for “coffee” could return results that aren’t nearby.) Even if you’ve turned off Location History in your Google account, you should still check out what app-level permissions you’re giving to Google apps and others in your settings.
On Android—and these directions are coming from a Pixel 3 running Android 9—open Settings, then go to Security & location, then Location, then click on App-level permissions. There you can change what apps are allowed to use your location info. Also under that Location field, you should be able to click on Advanced, and then see “Google Location History.” If you’ve already paused that, as described above, it should also be switched off here, if you’re signed into the same Google account on your phone.