I'm creating a web map with ArcGIS Online and have some points with the same address. I've seen some web maps where the overlapping points will separate with leader lines when you zoom closely to them (see image). This makes it easier to see that there are multiple features present and also makes it easier to navigate their pop-outs (rather than scrolling through them individually). Can this type of visualization be done with ArcGIS Online?
Unfortunately, this is not an 'off-the-shelf' option in ArcGIS Online symbology and you would have to create a custom application to achieve something like this. The point clustering options are also very limited. Check out this ArcGIS Blog post on Strategies to Effectively Display Large Amounts of Data in Web Apps.