This is a DreamArtist Textual Inversion Style Embedding trained on a single image of fall/autumn like colors. You can get amazing autumn/fall color effects in your images by calling Style-Autumn in the positive prompt, and if you want to temper the effect, also call Style-Autumn-neg in the negative prompt.
If you'd like the effect to come through stronger (some models need it), try bumping up the emphasis on Style-Autumn - see the images below.
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Props to Elldreth for the many hours spent figuring this all out with me! Go check his models.