H Titles Helps

I need you to help me understand something about the hierarchy of H titles. I know there should only be one H1 per page, my questions are: Can there be a h3 for example without H2? Or a H6 without H5? What factors are used to justify that a title is h2 and not h3? Should it be used whenever it makes sense from H1 to h6? Or what are the ways to measure how to use it, thanks in advance. And to be more niche, in the real estate sector, do you know of any example of the use of headings in text, internal linking and properties?