You basically either manage plugins yourself, or use a plugin manager like vim-plug.
Managing it yourself isn't hard if you know how to use Git. Just make a folder ".vim/pack/myplugins/start/" and then you can git clone any plugins into that folder you want. "myplugins" can be substituted with any name you want. Benefit is that it's simple and you have full control. Annoying part is you have to manually keep them up to date. It's not a bad option if you only have a few plugins you use.
Otherwise if you use something like vim-plug the benefit is you have a vimrc that describes all the plugins you want and it will do the work for you in managing them and keeping them up-to-date and selectively loading them.