enlarge the part that is between the red marks

Displace does not seem great in this case, but might be worth checking out nonetheless. 

To me it look like all you want to do is replace the center object not actualy resize the image. So isolate it and replace it

It is not possible to resize that image the way you want to without introducing sever distortion.  What you described will change all the objects in the image shapes you are changing all the objects in the image aspect ratio.  You seem to want to just change shape of images center object by changing the width of its content.  That is is easy but it will effect the Image composition.  The image will not be reformed the way you want.  What you want is not possible without introducing distortion.

You can change the image's center object shape change its aspect ratio just distort the center object. However that will effect the contents of the rest of the image for some part of its content will be  replaced or delete  by the center object's area size change.   You can select the center object and transform  it to distort it the want you want. That is easy to do. 

If  you select the full image and warp the center to the shape you want the outer  image area will also be warped it will be distorted and not the ways you want.

If you select each object and make then a layer you will not be able to create the composite you want without distorting each objects layer object shape  to conform the more center object changed shape. Each object shape layer must be adjusted to conform to previous center object shape change.

That's not an easy thing to do, but there is a workaround that might get you close.  It's also not easy for me to demonstrate because of the red lines, but you need to select the central shield area and save the selection. Give it a meaningful name like Center

Now release the select (Ctrl d) and go Edit > Content Aware Scale 

In the Options Bar use the dropdown for Protect and chose the selection you saved.

You can now hold down the ALt (Opt) key and drag any of the corner handles to expand the shield, and the central area will remain unchanged.

It would be a good idea to lay down some Guides before you use CAS to indicate the original size, and how much you need to expand it like this

I doubt you actually want to go there but the two options that seem at least halfway plausible to would be creating a Displacement Map (for using with the Filter Displace) or clipping the Frame and using Puppet Warp on the Smart Object. 

Both are probably problematic. 

Please post the actual image.