You can manage all media used from the Media > Library ] menu.
Media are stored in the wp-contents/uploads folder by year.
(If you delete a page or article from which the image was used, the uploaded original image is not deleted.)
You can set the default size of the image to upload from the [Setup ] > Media ] menu.
The default settings are set in WordPress, but you can make any changes you want.
Use when you need to raise a large number of images at the same time or when you need to upload the same size for all images.
After you add a file, set the title, alternate text, captions, comments, links, size, and so on for the file.
What is alternate text?
Indicates the actual name of the image and it is strongly recommended that you write it with a meaningful name for web accessibility.
[ Set Property Image ] The menu uses the selected image as a page, a thumbnail of the text. (may not apply to each theme)
[ Insert at URL ] The menu lets you import images into a URL without directly selecting the file. However, it cannot be used as a property image in this case.