The fonts that have the extra swashes, flourishes, and swirls for example typically place the extra characters in what is known as the Private Use Area (PUA). When a font is "PUA Encoded" this means you can easily access all special characters and load them into applications.
Not all fonts have special characters - but if you see the swashes displayed in the preview, you will also have access to use them!
How to Access Special Characters on Windows
Step 1: Install the font to your computer.
Step 2: Open Windows Character Map. This application is provided by default on all Windows computers. Just open your search tool and type out Character Map to find it.
Step 3: Open the application and select your font from the font dropdown.
Step 4: In the Group By section, select Unicode Subrange.
Step 5: In the Group By menu that appears, select Private Use Characters.
Step 6: Now you will see all the PUA encoded characters. Note: Sometimes you may need to scroll down a bit to find them all.
Step 7: If you want to use one or more in your application, you can click on the character > click select > and click Copy.
Step 8: Paste into your application and you are good to go!
How to Access Special Characters on Mac
Step 1: Install the font to your computer.
Step 2: Go to your Applications Folder and open the app called Font Book.
Step 3: In Font Book, find the font you wish to use and select it.
Step 4: Switch to the Repertoire preview by choosing View > Repertoire. Here you will be able to see all the available characters (including PUA characters!).
Step 5: Select the character that you wish to use and click CMD + C to copy the character.
Step 6: Paste into your application and you are good to go!