Meta Box

Thanks. I found it. I also wrote my own CSS Tweaks to further customize the look and feel and move the Gutenberg Editor below the MetaBox Custom fields boxes area.

/* Add Padding to Metabox Standard Style */
.postbox {color: #000 !important;}
.edit-post-meta-boxes-area .postbox {
border: 1px solid #ccc;
background-color: #f2f2f2;
margin: 0 0 ;
padding: 0 50px;
}

/* Move Gutenberg Editor Window below Custom Fields */
.edit-post-visual-editor {
background-color: #1e1e1e;
order: 10;
}

The previous post does not look like the images posted. Let's try this.

Gutenberg Editor: https://1drv.ms/i/s!AjHCE41XxAiZgZ1Yuqw_Ig-JIwjH0Q?e=oI6Pkd
Classic Editor: https://1drv.ms/i/s!AjHCE41XxAiZgZ1YIQd9ouJuMSwvEA?e=ao2JX2