I hope you are well today and thank you for your question.
Please enable the titlebar in the theme options then you can disable it in Posts and enable it for all Pages by adding the following CSS code in the Custom CSS code option of your theme on the below path.
If you want to disable it for individual posts then you can do so by editing the post and using its header settings as shown in the attached screenshot.
If you want to disable it on all posts then you can use the custom CSS code shared in the above reply.