Separate design for each gallery

Hi! I really need help
I recently purchased a template and in trying to redesign it for myself, I encountered some difficulties in designing the galleries

I am very bad at website development, so I really need someone’s help

I need to manipulate the pages of “projects” by changing the size and number of photos in a row
Ex: I would like to use 1 row of photos on one page, 3 rows of photos on another, 2 rows of photos on the third, and arrange them in some other way (I will give some examples below)

In general, I would like to manipulate the galleries more flexibly than I can do through CMS, because now changing one “project” page changes absolutely everything else

Maybe I need to unlink these pages from CMS,
Or maybe you have a better idea of how I could place my photos on the page
And that these changes on this page don’t affect the other pages

Here is my public share link: LINK
(how to access public share link)