how to initially zoom a map in angular google maps

Set zoom and center attributes. For example.

<agm-map zoom="8" [center]="10.3207886, 123.90250049999997">
    <agm-marker [latitude]="10.3207886" [longitude]="123.90250049999997"></agm-marker>
</agm-map>

center is usually to specify which area you want to concentrate on, according to it change zoom level

The update for agm-map does not support center directives anymore. use zoom and latitude and long instead.

<agm-map [zoom]="13"  [latitude]="127.1" [longitude]="141.1">
                <agm-marker [latitude]="127.1" [longitude]="141.1"></agm-marker>
</agm-map>