Hi,

Please go to Appearance → Customize → Custom CSS then add the following custom CSS code:

.open-mobile-builder-sidebar-nav .penci-builder-mobile-sidebar-nav,
.open-mobile-builder-sidebar-nav .close-mobile-menu-builder,
.open-mobile-builder-sidebar-nav .close-mobile-menu-builder {
    left: 270px;
}
@media only screen and (max-width:479px) {
    .penci-menu-hbg {
        width: 270px !important;
    }
}
.penci-builder-mobile-sidebar-nav {
    transform: translateX(-270px);
    -webkit-transform: translateX(-270px);
    -moz-transform: translateX(-270px);
}

You can change 270px with the size you want to show.

Regards,
PenciDesign.