@A2020,
So what I believe you’re seeing is your cache data. I believe you can simply clear this in-browser safely by going to Settings --> History --> Clear browsing data and selecting Cookies and site data.
There are also some sites that I believe use this to store temporary file information which may be contributing to the large size. I would try clearing browsing data via the browser itself first and see if the files disappear/the size decreases. Let me know if it does not.