Custom Link in menu to open new tab

Hi I’m using this Expositio theme from https://wpshower.com
this theme has no widget so the only way I found to add link to another site is via custom link in Menus.
However the ‘custom link’ in Menu only have ‘URL’ and ‘Label’ textbox to it so I can’t add the ‘target=”_blank”‘ to it.

here’s the URL to my mock-up site https://curlysuevintage.com/
I’m trying to make the ‘Blog’ button to a new tab.
Is there any other way for me to do this?

Thank You in advance.