Should we use different heading tags to get different font sizes in HTML?

There are two reasons;-

1)Heading tags are supposed to be used according to the topic’s importance in the webpage where as fonts are for sizes

2)If we use heading tags for font sizes then it would become difficult for us to rank our website.

You can read about head tags here:- https://developers.google.com/search/docs/fundamentals/seo-starter-guide#:~:text=SEO%20%2D%20Search%20engine%20optimization%3A%20the,our%20presence%20on%20the%20web.