How can I change the side admin menu items?

Hi,

I am trying to change the items that appear in the admin menu on the left side of the admin screens for site administrators.

Can you please let me know if/how this is possible.

Currently changing settings in the Branding > Admin Bar tab adds or removes items from the horizontal admin menu at the top of the page (but not the side menu).

Options will appear/ disappear depending on the user role capabilities set for that role - but I would like to create my own menus in the sidebar (as I can in the admin header bar)

Is there any way to change the content in the sidemenu of the admin pages?

Thanks
Chris