DPA have some fantastic information in their Mic University and their page discussing microphone set-ups for surround sound and immersive audio formats is a really great primer covering some of the common approaches:
https://www.dpamicrophones.com/mic-university/immersive-sound-object-based-audio-and-microphones
I’ve recorded using various multi-channel/surround techniques, but my most common approach for ambiences is using an IRT Cross. Although the technique is primarily designed for pairing with a front array, I actually enjoy it on its own as a quad format, and find it to be a pleasing compromise between envelopment, size of listening area, size and portability and localisation accuracy.