The glow effect illustrated in the image is typically achieved by rendering the stuff that glows by itself, bluring that texture one or multiple iterations, taking the luma component of the blurred texture and multiply the luma by the glow color or gradient map (color/tone mapping) and then add the resulting color to the original image. This is similar, but not equivalent, to what the Unity Image Effect Bloom does.
If you want to do something like that to UI text elements, you could (quick and dirty solution) I guess setup two overlapping text objects that are equivalent. Use white color for the first and total transparent color on the second with red outline and use a blur/glow/bloom filter/shader with addivitive blending on the outline to achieve something similar to what you posted as an image. Something like this is required if you want the red to bleed into both the white area and to the background.
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