Custom Headers & Lines

I am currently recreating my site using the Bedford template. Is it possible to add additional headers for me to use? For example, when I add a text object to the page, I can choose to format it using Normal, H1, H2, H3, or Code. Can I add an H4, H5, etc. to this dropdown? If not, how can I wrap my content in H4, H5, etc. without going into Developer Mode? Or is that even possible?

Also, is it possible to adjust the dimensions of an object? For example, I have added a line object to my page, but there's a lot of padding on the top and bottom of it. I want it to be closer to my text boxes. Can I adjust this somewhere without going into Developer Mode?

With heading, Do you want to change the style? or change tag for SEO purpose?

With padding, You can do with Custom CSS, without accesing Dev Mode.