The carrier can still roughly triangulate your position based on the signal strength. Not much you can do on that front but to go in airplane mode if you don't want to be tracked through the cell towers.
They don't even need to do triangulation nowadays, tower has direction and distance, because the way how 4G/5G work. 5G also has MIMO (meaning one burst of data to you carry data to other clients in same direction).
There even have been instances where some chinese phone manufacturers were abusing the emergency network while your phone is off to send user data to their servers ... so they could even triangulate your position while your phone is turned off.
Will it let me control when my location is shared with Google? Where I am, my carrier already knows my name, full address, and credit card information.
Imo apps knowing what city I am in is very different from apps knowing exactly where I am. While I wouldn't want to leak either my exact location or my city to someone that shouldn't have access to it, I don't really mind that much (compared to exact) if someone knows the city.
A weather app barely needs any accuracy so it shouldn't have it. But a navigation app does so it gets it.
Roaming happens when you connect to a different cell network than the one you have a contract with, not when your location data says you are in certain places.