popup on all sites

If it’s just the home page, this in a JS file/script somewhere should work as long as the hooks are loaded, but it fire before age gate:

AgeGateHooks.addFilter('age_gate_show', 'AgeGateHooks', (status) => {

    if (window.location.pathname === '/') {
        return true;
    }

    return status;
});

If it’s every page every time, then in functions.php:

add_filter('age_gate/cookie/set', '__return_false');