Some more context on why it currently works this way.
The idea of multi line plain text field in the CMS is to enable the user to enter text across multiple lines to make it easier for input. So it can be a convenient way to input, store and edit text that would be too long to fit into a single-line PlainText field.
However when rendering in the browser, this will just be plain text, wrapped up in the element that it is inserted into.
For example it could be a meta description in a meta tag, or text in a paragraph tag or a div element. An example of this can be seen in this browser inspector screenshot - Image 2020-08-03 at 2.28.29 pm.
To add any inline styling (including line breaks) to CMS content, use the Rich Text field instead.
It is also mentioned in the University lesson on CMS plain text.
Multi-line plain text fields in the CMS make it easier to enter text across multiple lines to input, store and edit text that wouldn’t fit in a single-line Plain text field. The text displays in the browser as plain text, wrapped in an element.
Hope this information helps.