Do apps have access to every image and file when they have files and media permission?

So on my phone some apps ask for file and media permission but does that give them access to their own folder only to store media and files in and everything is in containers or do they get access to every single file and media on my phone and would be able to send everything and store every information including my selfies and identify me?

access apps ask containers file files folder image media own permission phone privacy single store