Bloated WordPress Site

Hello,
I’m quite new to wordpress and sorry if this question is obvious to most! I’ve got some reseller hosting and thought I’d use it to install a few versions of wordpress and have a go with a few different themes plugins etc. They all have roughly the same amount of pictures, probably a dozen each, and slightly different plugins and themes but are now wildly different sizes ranging from less than 80mb to over 260mb. Is there a way I can see where this difference comes from? I can view the sites in my cpanel file manager but I’m not even sure which folders to start looking in for answers?
thanks in advance for any help.
Jim