I am sure everyone is aware about this. How do you increase your symbols in the legend ? I am using ArcGIS 10.3.1 and I am not sure about the newer version ( I will be getting the 10.5 in a few months). I am not sure if this is already fixed for the new version but for those who struggle to do this...
There is a topic about this on the GIS StackExchange that I have been searching for a solution....
ArcGIS 10.1 Legend - Increase Icon on legend without increase on map - Geographic Information System...
My suggest to you is to :
1) Add the Data Frame as a second one. Label it as a "For Legend Only"
2) Copy the layers to be use for the legend.
3) Keep the Data Frame out of the Layout View...
4) Fix the symbol while you are in the Second Data Frame...
So it doesn't mess up your symbols in the First Data Frame..
5) When you are done, insert each or all of your layers
6) Move them to your Layout View .
I hope that helps for everyone out there...
Happy Mapping !
P.S. If you have any other way around to do this , please make any comments...