You could try Life 360. The basic free version is pretty good for most families’ needs. It works by sharing the location of your smartphone. You can set it up to notify you when someone arrives at a location or leaves through GPS location. It’s also compatible with Tile Bluetooth trackers for finding things like your keys and wallet.
Note with any service like this, especially one that has a free tier, there is a trade off. The service provider will be looking to monetise your data. This is something that people are now becoming more aware of and providers are also making it more transparent about how your data is used. If this is something that concerns you, make sure to read the company Privacy Policy and see if you can opt out of the data sharing. In the case of Life360, you can opt out through the Do Not Sell My Personal Information page in the Life360 in-App Privacy & Security settings.