Hi there,
that Site uses two menus placed either side of the logo. Not so simple with Split to position them like so. But what you could do is to set a max width to the navigation which would bring the menus in closer, so go to Customizer > Additional CSS and look for:
.main-navigation:not(.slideout-navigation):not(.mobile-header-navigation) .main-nav > ul {
display: -webkit-box;
display: -ms-flexbox;
display: flex;
}
Update it to this:
.main-navigation:not(.slideout-navigation):not(.mobile-header-navigation) .main-nav>ul {
display: -webkit-box;
display: -ms-flexbox;
display: flex;
max-width: 800px; /* Adjust width to suit */
margin-left: auto;
margin-right: auto;
}