I would like for my customers to be able to upload images and preview them

I would like for my customers to be able to upload images and preview them in a pre-defined template.

Is there a plugin that I can add to my form?

You can use an image upload preview widget to allow users to upload an image and preview it before submitting the form:

https://widgets.jotform.com/widget/image_upload_preview

Thank you David. I think I need to explain further - I am hoping for an option for our customer to upload image(s) that would be in one of three a collage formats that we offer. Similar to below. 

Creating a collage from an uploaded image is not something that would be possible through JotForm.  The collage would need to be created before uploading the image and then uploaded through the form.