You can't embed the maps in an iframe directly; you would need to obtain an API key and use the Google Maps API:
Google Maps Platform | Google Developers
Based on my own experience, you will need to add a payment method to your account so that they can bill you if your usage exceeds the limits of the free tier.
There's also a "Maps Static API" for simpler integrations:
Overview | Maps Static API | Google Developers
You still need to create an account and add a payment method to use that.
There are free alternatives which you can
embed without setting up an account - for example: OpenStreetMap