In order to use TinyMCE self-hosted version, you need to download the latest version of TinyMCE package. It can be downloaded at https://www.tiny.cloud/get-tiny/self-hosted/.
For your information, below example is based on TInyMCE 5.2.0, so it may not work if you use different version of TinyMCE.
In my case I just upload all the files to /js on my webserver, so tinymce.min.js will be located at /js/tinymce/ usually.
List of content
Basic example to use TinyMCE
Below is a basic example based on TinyMCE 5.2.0.
<!DOCTYPE html>
<html>
<head>
  <script src="/js/tinymce/tinymce.min.js" referrerpolicy="origin"></script>
  <script>tinymce.init({ selector:'textarea' });</script>
</head>
<body>
  <textarea cols=80 rows=20>Chun Kang is genius !!!</textarea>
</body>
</html>
Hiding Benubar and Toolbar
You can simply hide menu bar and tool bar as below. For more information, please refer to https://www.tiny.cloud/docs/configure/editor-appearance/#menu.
<!DOCTYPE html>
<html>
<head>
  <script src="/js/tinymce/tinymce.min.js" referrerpolicy="origin"></script>
  <script>
  	tinymce.init({
  		selector:'textarea',
  		menubar: '',
  		toolbar: ''
  	});
  	
  </script>
</head>
<body>
  <textarea cols=80 rows=20>Chun Kang is genius !!!</textarea>
</body>
</html>
Select menu item based on your preference
<!DOCTYPE html>
<html>
<head>
  <script src="/js/tinymce/tinymce.min.js" referrerpolicy="origin"></script>
  <script>
  	tinymce.init({
  		selector:'textarea',
  		menubar: 'file edit insert format table tools help'
  	});
  	
  </script>
</head>
<body>
  <textarea cols=80 rows=20>Chun Kang is genius !!!</textarea>
</body>
</html>
Changing Skins by "oxide-dark" just like Sublime Editor
I wanted to find a option can show editor like Sublime Editor for coding test, and found a great options as below. This feature is only available for TInyMCE 5.1 and later. You may able to have more information at https://www.tiny.cloud/docs/general-configuration-guide/customize-ui/#skins
<!DOCTYPE html>
<html>
<head>
  <script src="/js/tinymce/tinymce.min.js" referrerpolicy="origin"></script>
  <script>
  	tinymce.init({
  		selector:'textarea',
  		skin: 'oxide-dark',
  		content_css: 'dark'
  	});
  	
  </script>
</head>
<body>
  <textarea cols=80 rows=20 style="background-color:orange;">Chun Kang is genius !!!</textarea>
</body>
</html>
Making tab key to insert indentation like text editor application
You simply do that by adding nonbreaking to plugins and set nonbreaking_force_tab=true
<!DOCTYPE html>
<html>
<head>
  <script src="/js/tinymce/tinymce.min.js" referrerpolicy="origin"></script>
  <script>
  	tinymce.init({
  		selector:'textarea',
  		plugins: "nonbreaking",
  		nonbreaking_force_tab: true
  	});
  	
  </script>
</head>
<body>
  <textarea>Chun Kang is genius !!!</textarea>
</body>
</html>
Forcing to insert <br> tag for pressing enter key
You can force inserting <br> tag instead of <p> tag when you press enter by foreced_root_block=false
<!DOCTYPE html>
<html>
<head>
  <script src="/js/tinymce/tinymce.min.js" referrerpolicy="origin"></script>
  <script>
    tinymce.init({
        selector:'textarea',
        plugins: 'nonbreaking',
        nonbreaking_force_tab: true,
        forced_root_block: false
    });
     
  </script>
</head>
<body>
  <textarea>Chun Kang is genius !!!</textarea>
</body>
</html>
Changing editor font, font-size, background color, font color
<!DOCTYPE html>
<html>
<head>
  <script src="/js/tinymce/tinymce.min.js" referrerpolicy="origin"></script>
  <script>
    tinymce.init({
        selector:'textarea',
        content_style: 'body { background: black; color: white; font-size: 10pt; font-family: 맑은 고딕체,Calibri,Arial,Sans-serif;; }'
    });
     
  </script>
</head>
<body>
  <textarea>Chun Kang is genius !!!</textarea>
</body>
</html>
Complete set of TinyMCE option for coding testing just like Sublime Editor
<!DOCTYPE html>
<html>
<head>
  <script src="/js/tinymce/tinymce.min.js" referrerpolicy="origin"></script>
  <script>
    tinymce.init({
        selector:'textarea',
        plugins: 'nonbreaking',
        menubar: '',
        toolbar: '',
        skin: 'oxide-dark',
        content_css: 'dark',
        nonbreaking_force_tab: true,
        forced_root_block: false
    });
     
  </script>
</head>
<body>
  <textarea>Chun Kang is genius !!!</textarea>
</body>
</html>