There’s a pinned post explaining well enough how to install and select a third party icon theme. In some cases though doing so will also change your menu icons. Not everyone will want this since the result can be quite garish so if you just want to change your home folder icons there is a way round. Be aware this is quite a tedious process and if you have a lot of items in your home folder you might not want to bother at all but….
First download your preferred theme. In my case I chose Pixel Perfect Folder Icons.
Extract the contents and then copy the ‘places’, ‘64’ folder to a location of your choosing.
Next right-click on each folder in your home directory individually and select ‘Properties’ followed by the ‘Set Custom Icon’ symbol.
Now navigate to your ‘64’ folder location, highlight which ever icon you want, click ‘Select’ and then close.
Repeat this process until you’ve changed all or how ever many folder icons you wish.
You can even mix the icon styles by downloading more than one theme.