Thanks for contacting us! There are a few ways to achieve this:
1. Try the various options within Effects > True Vintage for vintage-style distressed effects. Note that to apply to text, you need to click the Cog icon up the top right and then Combine everything.
2. Effects > Gritty gives a more subtle gritty feeling
3. Effects > Noise (and reduce the Fade) can add graininess to your image, as can Effects > Film Grain.
4. Some of the Seasonal > Halloween effects will be perfect for creating a grungy feeling, such as Ghostify (increase the fade for a more subtle effect), some of the Halloween Textures and Scary Movies.
Let us know if you have any further questions/suggestions!