You can easy set width to 0, it means 100% width and map will occupy its div
As for height - the same, but if you have modern templates with many nested divs - it can collapse and you'll not see map. You should set some fixed size for div
If your template have at least 2 nested divs - you'll get it collapsed.
You can set height not 100%.
Open map details, on "Advanced options" tab you can find item "CSS Class"
It is CSS class name for map div. By default I set my default class ("zhom-map-default"). You can override it in template, or you can enter your class name into this field. For example I enter MyMap
After that in template CSS define overide height like
height: 50vh !important;
In this case map div will be responsive for 50% of visible height