With macOS Mojave, you can implement Smart Folders, which automatically gather files by type and subject matter. They’re updated as you change, add, and remove files on your Mac. Here’s how to create a Smart Folder:
In the Finder, choose File > New Smart Folder. (Represented by the blue icon with the smiling face, the Finder is the home base for your Mac. You use it to organize and access almost everything on your Mac, including documents, images, movies, and any other files you have.)
To search for files, enter a topic, a phrase, or another parameter in the search field.
To determine whether the search should include only the names of files or their entire contents, choose “Name matches” in the search suggestions that appear below the search field, then click Name, then choose either Filename or Everything.
To search for additional specific attributes, click the Add button below the search field, then make choices using the search attribute pop-up menus that appear.
The menus work in pairs; for example, to search for images, you choose Kind from the pop-up menu on the left, then choose Images from the pop-up menu next to it.
Click Save, then specify a name and location for your Smart Folder.
If you don’t want your Smart Folder to be in the sidebar, deselect Add To Sidebar.
You can’t use certain characters, including punctuation such as a colon (:), in folder names. If an error message appears, try using another name.
To change the criteria for a Smart Folder, open the Smart Folder. Begin typing in the folder’s search field, or click the Action pop-up menu , then choose Show Search Criteria.
(This how-to is based on my experiences and info on Apple's support pages — where the images sometimes come from.)