try →
// Java
final String iosLocator = "**/XCUIElementTypeButton[`name == \"Allow Once\"`]";
driver.setSetting("acceptAlertButtonSelector", iosLocator);
try {
driver.switchTo().alert().accept();
} catch (Exception ignored) {
}
// or
// prepare args
HashMap args = new HashMap<>();
args.put("action", "accept");
args.put("buttonLabel","Allow Once");
// prepare command
String cmd = "mobile: alert";
// execute
try {
driver.executeScript(cmd, args);
} catch (Exception ignored) {
}