i know I've made Many battery complaints but this is actually ridiculous

You ran Fortnite for 23 minutes, but the phone\s been on and used for about 2 hours (at least). 8-1/2 hours isn't bad for just phone calls, texts and internet. (Don't compare Androids and iPhones, that's like comparing apples and mailboxes.)
 
Yes but an hour and a half of that screen on time was playing graphically intensive games. Doesn't seem too out of line. And we have no idea what any of your settings are. If you have your brightness cranked up, highest resolution for the screen, audio through speakers etc. etc. But most importantly, you can't compare battery life of a phone screen on time vs a tablet. Now THAT is ridiculous.
 
Based on your screen shot Fortnite would run for over 4 hours, 7% in 21 minutes is just over 20% an hour.

Also you are comparing 2 devices with completely different hardware and operating systems, depending which iPad you have the battery is 3 or 4 times bigger than your phone. The game may be better optimized and draw less power on an iPad. Point is its not an equal comparison.

And Fortnite is one of the most demanding games on mobile right now, it's a battery hog because it's pushing the hardware to its limits. Most Android phones aren't powerful enough to run Fortnite. I've played it on my S7 and Note 9, probably drains the battery faster than anything I've ever done.
 
A simple search of Google for Fortnight specs and gaming systems plus PC and Mac hardware requirements or Xbox gaming consoles. Building a PC with multiple GPUs us what gamers do to get Max frames and performance.

Buy the hardware for the task. Maybe iPhone XS Max us right for you, there's a thread on Note 9 forum even now. Or S10+ with Snapdragon 855. But I think it'll take a generation is two for mobile hardware to catch up to software. Always does.

It's a 1.0 teaser of what can be done. And even an i7 system runs hot. Mobile is throttled to 30fps.

I'm sure your iOS gaming forum is where you want to be. It a forum devoted to Fortnight game. Instead of multiple threads ranting about your Galaxy battery.