The hegemony of phone sensors has been the purview of Sony with their Exmor sensors for many years but now Samsung has started making inroads in the space with their ISOCELL chips. The latest is currently mass-produced and shipping in handsets already which is not a paper launch, but a real thing. The chip is capable of massive low light improvement compared to other sensors because it is essentially a near 1″ sensor with 1/1.12-inch measurements. This is close to what Sony RX cameras use as a main sensor, and a first for a phone.
As to how they are able to fit this sensor on phones, it is a dance between a protruding camera bump that is a little larger than usual and also a lens system that creates a full imaging circle from a minute distance. The GN2 is capable of recording 480fps in HD 720p, 4k 120fps, 30fps in 12.5MP windowed size and 10fps in 100MP mode which uses a clever algorithm and three RGB exposures to derive a 100MP image from the 50MP source.