A simple way to get close is to increase contrast and reduce saturation slightly.

Try this workflow in Photoshop:

1. Duplicate the background layer.
2. Set the duplicate’s blend mode to Overlay to boost contrast.
3. Add a Hue/Saturation adjustment layer and lower saturation a little.

If the Overlay layer makes highlights too harsh or blown out, either:

• reduce that layer’s opacity, or
• use a Levels adjustment instead and move the black point inward to deepen contrast more gently.

There are also downloadable Photoshop actions made to emulate Instagram-style filters, which can be a fast starting point if you want one-click versions. From there, fine-tune contrast and saturation to match the exact Lo‑Fi look you want.