Is there a way to find how much RAM is installed in my iOS device?
There are a number of free apps that will provide more information about your device’s internals. Lirium Device Info is one of the better ones.
From the top-left menu, open This Device → System for details about your device’s RAM. For instance an iPhone 7+ has 3 GB of RAM:
Note: I am not affiliated with this app or its developer.
Go to EveryMac.com's Ultimate Mac Lookup, enter one of the listed iDevice numbers or identifiers, hit lookup and you will get the RAM size.
Please check the *: Apple provides no official details regarding RAM used by the %iDevice%...
Various sites compile nice single page summaries. The RAM across devices is listed just below the top horizontal line: