Can we create a general content region in the template which is where the page content goes, and then fill that content region with a complex layout using the page editor?
@insightdes Ghost’s editor is a content editor, not a site/page designer. There is no layout feature other than what you manually code in your template files with html/css/handlebars.
As @naz said above, if you need blocks of editable text content then you could use the {{#get}} helper to fetch specific posts/pages and insert their content into your template file. If you go that route it would be worth reviewing the routing docs so that you can exclude those posts/pages from appearing as individual pages on your site.