Look at the addnewpage plugin. It says it has not been updated recently, but it still works quite well. You could put the plugin markup in a sidebar or use the
site template technique and place it in your template:
<?php echo p_render('xhtml',p_get_instructions('{{NEWPAGE}}'),$info) ?>
See:
https://www.dokuwiki.org/plugin:addnewpage#site_templates
The latter works well in the footer (footer.php in the dokuwiki template);
The plugin is very simple to install and use.