Create a Temp File in the Temp Folder

public static class TempFileCreator
{
    public static void CreateTempFile(string filePath)
    {
        using var sw = new StreamWriter(filePath);

        sw.Write("...");
    }
}

Creating a Temp File Using the GetTempPath() Method

var tempFile = Path.Combine(Path.GetTempPath(),"text.txt");
Console.WriteLine($"Creating temp file: '{tempFile}'");
TempFileCreator.CreateTempFile(tempFile);

Creating a Temp File Using the GetTempFileName() Method

tempFile = Path.GetTempFileName();
Console.WriteLine($"Temp file '{tempFile}' exists? {File.Exists(tempFile)}");
TempFileCreator.CreateTempFile(tempFile);

Creating a Temp File Using the GetFolderPath() Method

var appDataPath = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
tempFile = Path.Combine(appDataPath, "text.txt");
Console.WriteLine($"Creating temp file: '{tempFile}'");
TempFileCreator.CreateTempFile(tempFile);