Googleマップの共有URL、または lh3.googleusercontent.com の画像URLを貼り付けると、最大解像度版を取得します。
https://www.google.com/maps/place/.../data=!3m8!1e2!3m6!1sAF1Qip...!6shttps:%2F%2Flh3.googleusercontent.com%2Fp%2F...%3Dw203-h142-k-no!7i1179!8i830!...
https://lh3.googleusercontent.com/p/AF1Qip...=w203-h142-k-no
https://lh3.googleusercontent.com/gps-cs-s/APNQ...=s1360-w1360-h1020-rw