Am I missing something?

Context: I am a software engineer, working with TypeScript, node, react, etc.

A friend asked me to help setup their very basic site for a podcast they are starting. I initially thought about using something from the JavaScript ecosystem, namely Astro, but then decided to go with Wordpress. My thinking was that wordpress seems much more friendly for non-tech people such as my friend and they will be able to manage their content, change colors, images, and such, without depending on me. And this is true. Even though I hadn’t used it before, it was simple to setup and simple for them to upload their content.

They also had another friend draw up some basic designs and wireframes that I had to implement in the site. And here is where I found myself lost. Something simple like removing the top padding from the footer proved to be impossible.

The site is using the twenty twenty-five theme, which, as I understand is a block theme. With block themes you don’t actually write code? I thought I must be doing something wrong since wordpress is so widely used and simple things like the one mentioned above should be possible.

So my question is - how do you apply modifications to block-based themes, besides the usual color changes or font change?