In the single blog post, I disable the post’s title and add the Heading 1 tag, and wanted to use it as a new title. Please let me know if I can move heading 1 above the featured image. Now it’s below the image by default.
you would have to add the Image in the Post Content using an Image Block.
Keep the Featured Image also selected, then go to Customizer > Layout > Blog –> Featured Images >>> Posts (tab) and uncheck: Display featured images
This will remove the featured image from the single page ( so you don’t have two image ), but it will keep the featured image for your Blog / Post Archives.