This is an example of setting the device mode with height width and scalefactor with devtools and selenium4

SetDeviceMode.java

package com.devtools;

import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.devtools.DevTools;
import java.util.HashMap;
import java.util.Map;

public class SetDeviceMode {

    final static String PROJECT_PATH = System.getProperty("user.dir");

    public static void main(String[] args){
        System.setProperty("webdriver.chrome.driver", PROJECT_PATH + "/src/main/resources/chromedriver");
        ChromeDriver driver;
        driver = new ChromeDriver();

        DevTools devTools = driver.getDevTools();
        devTools.createSession();
        Map deviceMetrics = new HashMap()
        {{
            put("width", 600);
            put("height", 1000);
            put("mobile", true);
            put("deviceScaleFactor", 50);
        }};
        driver.executeCdpCommand("Emulation.setDeviceMetricsOverride", deviceMetrics);
        driver.get("https://www.google.com");
    }
}