Make a Photo Look Like a Miniature Model.

Open a photo in PS.

Turn on Quick Mask Mode.

Select > Edit in Quick mask Mode.

Select the Gradient Tool.

Make sure Reflected Gradient is selected.

Double Click in the Edit Gradient box.

Make sure gradient is Black to White.

Create a Gradient Mask over the parts of the photo you wish to remain in focus.

Turn off Quick Mask Mode

Go to Filter > Blur > Lens Blur

Adjust to suit the image.

Enter.

Deselect Control (Command) D

Go to Image > Adjustments > Hue /Saturation

Bump up Saturation  30 - 40 %

Go To Image > Adjustments > Brightness Contrast

Increasing Contrast may improve effect.