DevExtreme Angular - Customize the Appearance

You can configure the drop-down field using the dropDownOptions object that contains fields described in the Popup Configuration section. You can also specify a custom template for the drop-down button in the dropDownButtonTemplate option.

jQuery
JavaScript
$(function () {
    var fruits = ["Apples", "Oranges", "Lemons", "Pears", "Pineapples"];
    $("#dropDownBoxContainer").dxDropDownBox({
        value: fruits[0],
        dataSource: fruits,
        dropDownOptions: {
            title: "Fruits",
            showTitle: true,
            fullScreen: true,
            showCloseButton: true
        },
        dropDownButtonTemplate: function() {
            return $("<img>", { src: "images/icons/custom-dropbutton-icon.svg", class: "custom-icon" });
        },
        contentTemplate: function(e) {
            var $list = $("<div>").dxList({
                dataSource: e.component.option("dataSource"),
                selectionMode: "single",
                onSelectionChanged: function(arg) {
                    e.component.option("value", arg.addedItems[0]);
                    e.component.close();
                } 
            });
            return $list;
        }
    });
});
Angular
HTML
TypeScript
<dx-drop-down-box
    [(value)]="selectedFruit"
    [(opened)]="isDropDownBoxOpened"
    dropDownButtonTemplate="dropDownButtonTemplate"
    [dataSource]="fruits">
    <dxo-drop-down-options
        title="Fruits"
        [showTitle]="true"
        [fullScreen]="true"
        [showCloseButton]="true">
    </dxo-drop-down-options>
    <div *dxTemplate="let contentData of 'content'">
        <dx-list 
            [dataSource]="fruits"
            selectionMode="single"
            (onSelectionChanged)="changeDropDownBoxValue($event)">
        </dx-list>
    </div>
    <div *dxTemplate="let data of 'dropDownButtonTemplate'">
        <img src="images/icons/custom-dropbutton-icon.svg" class="custom-icon">
    </div>
</dx-drop-down-box>
import { DxDropDownBoxModule, DxListModule } from 'devextreme-angular';
// ...
export class AppComponent {
    fruits = ["Apples", "Oranges", "Lemons", "Pears", "Pineapples"];
    selectedFruit = this.fruits[0];
    isDropDownBoxOpened = false;
    changeDropDownBoxValue = function (args) {
        this.selectedFruit = args.addedItems[0];
        this.isDropDownBoxOpened = false;
    }
}
@NgModule({
    imports: [
        // ...
        DxDropDownBoxModule,
        DxListModule
    ],
    // ...
})