Both are possible, you just need to specify the correct parent
Below appearance set the parent = themes.php
or you can use my add-on plugin that lets you add options pages through an admin interface: https://github.com/Hube2/acf-options-page-adder
I’m currently looking for feedback on a new version that also duplicates field groups for use on multiple options pages: https://github.com/Hube2/acf-options-page-adder/tree/Fieldset-Duplicator
