Customize Responsive code

I need responsive customize code for my site in which I can easily set up responsive images in the same size and pixels. 
Kindly help in this issue and guide me about it. 
Really thankful. Thanks
 

Could you be more specific? Responsive how? "Same size and pixels" is the opposite to responsive? What are you trying to achieve? Can you share your website?

• My website is https://www.grilldesire.com/
   basically i make a top pick blocks on every page but the problem is the picture in blocks. The pictures are not setting up in the same size somewhere it shows pictures are too big and somewhere it shows pictures are in different sizes thats creating an issue.
  I want that the pictures present in it are must be in the same size and responsive shapes. May be now you understand.

I understand a little more, but not completely. Main problem is you are on a forum for help with Squarespace websites, and your website is built on WordPress. I suggest that you contact the website designer or template designer.