For Fortnite, FIFA and Fall Guys, an i5-12400F + RTX 4060 + 16GB RAM should be more than enough for smooth 1080p gaming and should last the kids several years. I’d focus more on getting a decent PSU and motherboard rather than paying extra for 32GB RAM right now, since RAM can always be upgraded later. If the PC price doesn’t include Windows, you can also get a Windows 11 Home key separately instead of paying the full retail license price.