We cannot visually write the HTML for the enclosed content.
However you can write the HTML somewhere else and copy paste it between [sc name="myshortcode"] <my html> [/sc]
I believe, the break tags are added by the block editor. I would suggest insert the HTML in a single line.
I agree that the code would be difficult to read for bigger HTML, but if we are using this enclosed content shortcode for bigger HTML then it means the shortcode content need to be optmized to ensure minimal external input.