This script iterates the Google Analytics trackers on the page (assuming the Google Analytics variable is 'ga'. It then outputs various bits of info, including the tracker name, the tracking ID, the client ID, the cookie domain and any custom dimensions that exist. Copy and paste it into the console on the page you want to find out more about.

GA Tracker helper

if(window.ga) {
    var arr = window.ga.getAll();
    
    for (var i = 0, len = arr.length; i < len; i++) { 
        var t = arr[i];
    
        if(console.group) {
            console.group(t.get('name'));
        }
        console.log('Main tracker object:', t);
        
        // let's find the object that has the data object inside it so we can present more info
        var trackerData;
        for ( key in t ) { 
            if(typeof t[key] == 'object' && 'data' in t[key]) { 
                trackerData = t[key].data;
                break;
            }
        }
        if(trackerData) {
            // the data var does not exist on the classic tracker
            console.log('Data within tracker:', trackerData.values);
        }
        
        console.log('Tracker name:', t.get('name')); 
        console.log('Tracking ID:', t.get('trackingId')); 
        console.log('Client ID:', t.get('clientId')); 
        console.log('Cookie Domain:', t.get('cookieDomain'));
        console.log('Allow Linker:', t.get('allowLinker')); 
        console.log('Linker Parameter:', t.get('linkerParam'));
        
        if(t.get('&gtm')) {
            console.log('GTM Container ID:', t.get('&gtm'));
        }
    
        // create an array of up to 20 dimensions
        var dimensions = [];
        for(var j = 0; j < 20; j++) {
            var dimensionName = 'dimension' + (j+1),
                dimensionVal = t.get(dimensionName);
    
            if(dimensionVal) {
                dimensions.push({name: 'Dimension ' + (j+1), val: dimensionVal});
            }
        }
    
        // if there are any dimensions in the array - iterate them, echoing them out to a new group
        if(dimensions.length > 0) {
    
            // start a new (nested) group
            if(console.groupCollapsed) {
                console.groupCollapsed('Custom Dimensions');
            } else if(console.group) {
                console.group('Custom Dimensions');
            }
    
            for(var k=0,klen=dimensions.length; k < klen; k++) {
                console.log(dimensions[k].name + ':', dimensions[k].val);
            }
    
            // end the nested group
            if(console.groupEnd) {
                console.groupEnd();
            }
        }
        
    
        if(console.groupEnd) {
            console.groupEnd();
        }
    }
} else {
    console.error('Error: Google Analytics object not present or not named "ga".');
}