As a shortcode parameter no, but with simple CSS and a dark tile provider you could achieve what you want.
You can find a list of free providers here, and this one is dark: https://leaflet-extras.github.io/leaflet-providers/preview/#filter=Stadia.AlidadeSmoothDark
As for the zoom and fullscreen controls, you can add custom CSS to your theme :
.travelersmap-container .leaflet-control-zoom a, .travelersmap-container .leaflet-control-fullscreen a {
color: white !important;
background: rgba(0, 0, 0, 0.5) !important;
transition: all 0.5s ease;
}
.travelersmap-container .leaflet-control-zoom a:hover, .travelersmap-container .leaflet-control-fullscreen a:hover {
color: white !important;
background: rgba(0, 0, 0, 0.9) !important;
}