The iPhone is not the obstacle here — everything you need runs in a browser or cross-platform app. Three routes, cheapest first.
Google Maps sharing, free. On the Android phone, Google Maps > profile > Location sharing > New share > choose the iPhone user's Google account. Accept on the iPhone in Google Maps, and the contact appears on the map with a last-updated timestamp. No installs, works across carriers, and the Android user can stop sharing whenever they want.
Family Link, free, for a child's account. Install Family Link on your iPhone, sign in as the parent, and add the child's Google account. You get live location, location history, app install approval, screen time and the ability to lock the device. It is Google's supported answer and it is visible on the child's phone.
A monitoring dashboard, paid, for content. If you need messages and call logs rather than a dot on a map, an agent has to be installed on the Android device once, physically. Ultimate Phone Spy covers Android 4.0+ (root only needed for WhatsApp and some social apps), and you open the dashboard from Safari or Chrome on the iPhone (system requirements, plans). There is no remote install — that is not a limitation of this product, it is how Android works for every product in the category.
Three things that trip people up: Samsung's aggressive battery management kills background location unless you exclude the app; Google's own sharing pauses if the Android user turns off location; and geofences are more reliable than live tracking for battery and accuracy reasons.
We covered the same setup with more detail in this thread — the steps do not change based on which iPhone model you are using.