If enabled it will force the VAE to run in float32 for high image resolution pipelines, such as SD-XL. VAE
can be fine-tuned / trained to a lower range without losing too much precision, in which case
`force_upcast` can be set to `False` (see this fp16-friendly
[AutoEncoder](https://huggingface.co/madebyollin/sdxl-vae-fp16-fix)).