Use activation token portrait+ style at the start of your prompt to incite the effect.
This is a dreambooth model trained on a diverse set of close to medium range portraits of people.
The goal was to create a model with a consistent portrait composition and consistent eyes. This model can do several styles, so you'll want to guide it along depending on your goals. Note below in the document that prompting celebrities works a bit differently than prompting generic characters, since real people have a more photoreal presence in the base 1.5 model. Also note that fantasy concepts, like cyberpunk people or wizards, will require more rigid prompting for photoreal styles than something common like a person in a park.
Portrait+ works best at a 1:1 aspect ratio, though I've had success with tall aspect ratios as well.