First, you might not understand the lines setting on the textarea field, this is just the initial lines shown, unless you are talking about the character limit settings, and this would not work very will when using html because all of the code would count as added characters.
The WYSIWYG field has a setting for full or basic to limit the controls that are available. In addition to this the controls can be alter using a filter as described here https://www.advancedcustomfields.com/resources/customize-the-wysiwyg-toolbars/
The developers don’t visit this forum, if you want to suggest this to them you need to contact them here, open a ticket in your account, or make a suggestion here.
