how to create page title become h1 automatically ?

Hi there,

GP adds the page title as <h1> by default.

Have you created a layout element that might be disabling it?
https://docs.generatepress.com/article/layout-element-overview/

If not can you disable all plugins except GP premium for us to take a look?

I did. I disabled content title for every page because it looks bad in the page.

How to not disabled content title but hidden in the front end ?

We could use CSS but generally, that's not a good idea for SEO, especially for the page title.

so, i have to create it manually in the page ?

You could consider creating a page hero:
https://docs.generatepress.com/article/block-element-page-hero/

With dynamic data and GenerateBlocks:
https://docs.generatepress.com/article/dynamic-data/

If not then yes you would need to add it manually using Kadence.