Is it possible to pair 4 Anker Soundcore 2 with each other to a mobile phone?
No. 2 is the max and you need to have the same iterations as well
If you have the soundcore 3 though, it has party cast which would allow you to connect up to 100 speakers with the partycast features. I had a Flare 2 and 2 soundcore 3 paired together.
Not 4 only 2 (stereo)
If you want to pair 4 you need speakers with so called partycast feature.
Take a look at soundcore’s speaker list to find those.