Some people like the idea of using a "plugin manager". I once used a thing called "pathogen", but it vanished, and I switched to "vundle". You do not need to use a plugin manager at all, especially if you understand vimscript.
Back when I used plugins, they went into the ".vim/bundle" directory.
At this time I am ditching all my plugins and investing time learning how to work with vimscript. I once had several plugins: taglist and nerdtree. And I used "vundle" to manage these and to be ready for others I thought I might find interesting. My interest in these date back to when I was stupid enough to try using "ruby on rails". I won't get into all the pain and misery that led to, but now that I have left that disaster behind, I no longer "need" these plugins.
If you do get interested in plugins, you should consider a plugin manager. The basic idea is that rather than dumping all your plugins into your .vim folder, it allows you to keep each plugin in its own directory. Not necessary, but widely recommended.
I used vundle, many like vim-plug. There is also fugitive. There are probably others to consider in this day and age.
If you decide to do things with plugin and a plugin manager, read the documentation before diving in.
Tom's vim pages / [email protected]