To copy data from one wp website and insert into a new wp theme

I have an existing website that's working with Wordpress.
I would like to make a new wp install and new theme , then copy the content across.
It would need rearranging and some small changes to images and text to make the content match the new theme.

Or if it would be easier to install the theme and the customise it.

I do need somebody creative to work out the best way the site should look.
All the pages , images and data are already online and are working.
I am using yoast seo so I think the best way is to export the data from the existing Wordpress install.