5.3 default installation is 60Gb.
Maybe you have installed some plugins? The default plugins in my folder are 23Gb from that 60Gb total
Check Plugins → Bridge. The Megascans can be really heavy, even a random rock can take several Gb in size.
But someone that has 5.4 should check the folder size for OP, I don’t have 5.4 to check but 30Gb is not a realistic scenario.