Maybe the package you want is only on the aur or you just want some special version but you don't know how to CORRECTLY install aur packages, well you've come to the right place! In contrast to what many use you don't need some extra package manager, pacman is the only one you ever need, start by installing the following software (if you don't have them already)
sudo pacman -S git binutils make gcc pkg-config fakeroot cmake wgetNow make a folder somewhere named "programs" (or some other name if you prefer) and clone the software you want into there, e.g
git clone https://aur.archlinux.org/zsh-theme-powerlevel10k-git.gitnow go into that folder and run
makepkgand finally when it's done install the package via
sudo pacman -U *.zstAnd you're done!