For example, like the Impact font in the attached image you’d usually see in memes. The most customization I could find was simply choosing the text color and font.
Use bitmaps fonts instead of .ttf fonts.
Hi, I do not know, WFS seems not to provide such feature. Bitmap font is sure solution, but if you are lucky maybe you can find a font familiy, that is stackable/layerable and suits your needs. Example: Bungee Font Family · 1001 Fonts
Then you would only make duplicate of your text and choose the fonts in right order.