I am sorry for not being clear. This is about an article page content font size, yesterday I asked my dad to read the article from a website but he couldn't read it properly because of the small font size, then I checked for a zoomIn option but this option is not available in Chrome. I checked some of the other sites but none of them have font change options. It's a common feature I wonder why no one has it Or is there any good reason behind it?
If you mean different sizes between different devices resolution (width x height), the answer is YES!
Smaller device may require bigger font size
If you mean different sizes between Title, Subtitle and content the answer is YES!
*Titles > Subtitles > content *
If you mean different sizes between Title of same level but different pages, the answer is NO
You can lose your identity and standardization