The only way that a user could change from H2 to something else is by creating an override of the layout. So surely they would be able to either add a new class then or just update the CSS.

or use something like

.blog .page-header [itemprop="name"]
{
	background-color:green;
}

But I don't know if all browsers support that.

@brianteeman

100% Agree with you.
But some disadvantages of the overrides.

1. Increase the template size.
2. If Joomla will change in blog_style_default_item_title.php. Then the user must also do it in the overrides.
3. Always check the blog_style_default_item_title.php file when he/she can update the Joomla Version.
4. Time Taken.

Very helpful for developers if Joomla will provide a class with a heading tag

1. We have layouts so that you can override things.
2. With Joomla 4 we have a really cool override check on update now
3. Its not helpful, because in the scenario you described (changing the h2 to h3) that can only be done in a layout.

@brianteeman
I don't want to change the heading tag from h2 to others. Because the h2 tag is good for SEO.

But the font-size of h2 is 30px but am want to 24px. Now I have no specific class so I can create a strong selector. If I create CSS selector like
.page-header h2 {}
Then this is not a good CSS selector.

So that's why am asking to add the class on heading tag. So the developer can use that class for a CSS selector.

It is helpful. If we do this.

Thanks,
Chandan

@brianteeman

Any update?

still not convinced

@chandanndeep @ReLater already should you a solution that does more or less the same as a class.

.blog .page-header [itemprop="name"]
{
	background-color:green;
}

But I don't know if all browsers support that.

this should work for all browser.

Thanks @brianteeman