A number gives you a carrier and a region, nothing more. Live location comes from the phone's OS or the carrier's network, and both require the account holder or the device owner to authorize it — so the real question is which authorization you have, not which website to try.
If the person is on your mobile account (a child's line, a partner who agreed to be on the family plan), the carrier's own family service is the correct tool: Verizon Smart Family, T-Mobile FamilyWhere or AT&T Secure Family. Accuracy is cell-tower level — hundreds of meters in cities — and every one of them notifies the line owner that location sharing is active.
If you administer the device, a monitoring app installed on it is legitimate and gives better data than carrier tools: location history, geofences, messages, call logs. Ultimate Phone Spy covers Android, Windows and Mac from one dashboard (location tracker, pricing). Installation is a one-time physical step on the device — there is no remote install, for anyone, on any platform.
If the person is an adult who has not agreed, there is no lawful option and the search results you will find are scams or malware. Reverse-lookup sites sell public records; "enter a number, see a map" pages collect card details and deliver nothing.
We covered the same question from a few angles in this thread, including what each tool actually requires and how accurate it is, so this reply stays short. The one-line version: consent or administration first, then pick the tool that matches the platform.