According to 9to5Mac.
'GeekBench benchmarks confirm iPhone 7 Plus ships with 3GB of RAM, faster than 12.9″ iPad Pro'
The iPhone 7 plus would ship with 3Gb of Ram.
If so this is the highest Ram put into an iPhone.
Link > iPhone-7-plus-3gb-ram-geekbench-benchmark.
"After much speculation that the iPhone 7 Plus would include an extra GB of RAM, bringing its total to 3GB, a new GeekBench benchmark for the iPhone 7 Plus (iPhone9,4) confirms the amount.
The iPhone 7 Plus is thus the first iPhone to come with 3GB of RAM, making it the largest amount of RAM to appear in an iOS device outside of the 4 GB-infused 12.9″ iPad Pro."
Current Phone >
Samsung Galaxy s²³ Ultra 512gb Phantom Black.