To elaborate a bit more, from what I have observed, Samsung based B3/B20 sites as well as the new poles of wonder/5G enabled building or lattice towers seem to be 4x4 enabled, whereas the older swaps from Samsung to Huawei with 'basic' 2100Mhz refarm from 3G to 4G B1 (basic in the sense that no other bands are added, nor antennas replaced) then they seem to remain 2x2.
On the subject of antennas, if you are able to see (or photo a closeup of) the feeders into the bottom of the antennas you should be able to determine if they're 2x2 or 4x4 MIMO due to the number of connections.
Actually being able to use 4x4 MIMO, assuming your device is capable of it on the bands being broadcast, is also difficult, rank 4 (all 4 streams of 4x4 MIMO) is rare and needs almost ideal signal metrics. Rank 3 (3 streams of 4x4) is somewhat easier as it needs less ideal signal conditions, and so on.