On danbooru, after searching for a tag there is a button at the top right of the screen that lets you change the size of the images, is there something similar here? The default size is slightly too small and I don't want to have to open every single image I'm interested in.

Yes you can,in the account options,try checking the box for the show original size,and save,and boom,you got them just the way they are meant to be.

Thats not quite what im looking for, that changes the image after I click it but I want the images to be bigger in the list before I click it.

You may also need to check "Disable Image Constraint".

I understood the message from "boorubrowser11" and I agree with him, there is no choice of image width in the main page (index.php) which displays the different images like danbooru.
I checked "Disable Image Constraint" and save but that's not what we wish for, idk if you truly understand what is the 'problem'.

Well.. the answer is probably "no" then.

Correct Pon. And the disable image constraint feature only works on posts.

I also noticed that when you enable that option you lose the ability to see full size images on posts. The click for full size disappears and the site only loads a sample.

userstyles.world/style/3144
Could try getting a webpage style modifying extension like Stylus and install this

Not ideal, but you can zoom in on the whole site using ctrl +