Open a new tab in an existing browser session using Selenium

This may not works:

driver.FindElement(By.CssSelector("body")).SendKeys(Keys.Control + "t");

Alternative: Find clickable element with target blank (search for "blank" in page's surce code). This will open new tab.

Than switch between tabs (thanks @Andersson) with:

driver.SwitchTo().Window(driver.WindowHandles.Last());
driver.SwitchTo().Window(driver.WindowHandles.First());

We can simulate Ctrl + Element Click

Actions action = new Actions(_driver);
action.KeyDown(Keys.Control).MoveToElement(body).Click().Perform();

Reference:
https://www.codeproject.com/Answers/1081051/Open-link-in-New-tab-using-Selenium-Csharp-for-chr#answer3

To handle new tab you should switch to it first. Try following:

driver.FindElement(By.CssSelector("body")).SendKeys(Keys.Control + "t");
driver.SwitchTo().Window(driver.WindowHandles.Last());
driver.Navigate().GoToUrl("http://www.google.com")

Also you might need to switch back:

driver.SwitchTo().Window(driver.WindowHandles.First());

Sending Keys.Control + "t" didn't work for me. I had to do it with javascript and then switch to it.

((IJavaScriptExecutor)driver).ExecuteScript("window.open();");
driver.SwitchTo().Window(driver.WindowHandles.Last());