Epic badly need a FAQ for this and so many other things 
… Anyway if you do some more research, you’ll see you can dial back the options. So its possible to get close to 30gb (with symbols excluded ofc). But here’s the catch. During first install (and crucially the first run), space needed can balloon to multiples of that. HINT: Multiple DDC, Paging-file, temp install files. 
BTW:
For anyone else coming to the thread, you can strip down the engine manually after. There’s doc zip files that can go, plus experimental plugins plus unused platforms (Android). So it may be possible to get down from 30 to 20 to even ~10gb.
The issue is the Paging-File and DDC often become really bloated. DDC in particular needs to be cleaned out from time to time (Paging too). Sadly never found the DDC none / cold runtime settings helped much though (in the editor at least).
Also, if buying or upgrading gear, try to get 2TB SSD for UE5 (1TB SSD for UE4). As you need to account for content packs ahead of time. So try to get a cheap HDD external drive now too, as it’ll really take the pressure off later. See here & here…