And because your ISP-provided IP address will only show connections to the VPN provider’s servers. If your VPN provider doesn’t keep logs, then the FBI can’t acquire any relevant data from the VPN provider. (And if the VPN provider is based in another country, it’s an even more difficult process.)
The FBI can go to Google to acquire the IP addresses of any device that performed searches of whatever, at this or that time, but if the subject didn’t use Google’s search engine (and didn’t allow any Google scripts to run in their browser), they won’t get the right subject. The FBI can demand information directly from the website owner, but at most they will get the VPN server’s IP again and perhaps activity conducted on the site from someone connected to that VPN server .
The FBI can serve court orders on Apple or Google for your phone activity and cloud data. Or they can serve the mobile carrier for location data and call/text metadata. (Silly amateur bank robber!)
Of course, law enforcement/government agencies can seize your devices if they have justification that will convince a judge, or if you’ve been arrested. Then they can use forensics to try and recover what you were doing and when on all your devices.
If you were a serious person of interest before, then the FBI or other government agency could put some kind of authorized intercept mechanisms in place, or try to compel providers to send your digital activity to them in near real time.
So if you do want to rob a bank, don’t be the typical clueless internet user. And leave your phone at home when you go to another town to buy that furry sex costume… and pay with cash, of course. 
(You still might get caught, though.)