Right now, the only method I found is to click on the expando, then right click on the image and open it in a new tab. Is there a way to make it so I can just click it once? I can't imagine any possible scenario where I'd want to see a large but not full size image.

I'm using the browser on my computer if that's relevant.

Edit: I got it to work using the Stylus addon and:

.img-expanded:not(.banner, .avatar-overlay) {
    max-height: unset;
    max-width: 100vw;
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    outline: auto;
    outline-color: black;
    z-index: 1;
}

I also made it outline any expandos with:

/*Note: Links are exactly the same except without bg-transparent, so using not(bg-transparent) instead will outline the links instead of the expandos. Also, they're outlined orange unless you change it, so you could take that off, give them all outlines, and you can tell which they are based on the color.*/
.thumbnail.rounded.overflow-hidden.d-inline-block.position-relative.p-0.border-0.bg-transparent {
    outline: auto;
}