Code Field is a Craft CMS field type that uses the craft-code-editor package to provide a modern code editor for content authors.
That means it provides code highlighting, syntax checking, and autocompletion for over 80 languages.
It also has light, dark, and high contrast themes that can be chosen on a per-field basis.
It also sports as a variety of editor options such as font size, line numbers, code folding, and more.
You can convert existing text/code fields over to Code Field fields while retaining your content.