In case you want to have the galleries in a post in a masonry format, you may find an instruction here:

If you want all images in a gallery to have the same size...
... just add the following CSS rule via the Custom CSS tool:
.gallery__item {
flex-grow: 0 !important;
}
How to remove the Featured Image from individual posts?
Create an override theme folder (https://getpublii.com/dev/theme-overrides/). Copy the config.json file into it.
Open the config.json file in your override folder using your preferred editor. Look for “postConfig” and edit the “featuredImageWidth” section so that it looks like this:
"postConfig": [ { "name": "featuredImageWidth", "label": "Featured Image Width", "value": "post__image--wide", "type": "select", "options": [ { "label": "No Image", "value": "post__image--none" }, { "label": "Normal", "value": "post__image--normal" }, { "label": "Wide", "value": "post__image--wide" }, { "label": "Full", "value": "post__image--full" } ] },
The essential part is { “label”: “No Image”, “value”: “post__image–none” }.
Next, you need to add custom CSS in the Publii app (Tools & Plugins > Custom CSS):
.post__image--none { display: none; }
Once you’re in the post editor, you’ll see an option for the Featured image to display “None” images

How to create a post template that loads posts based on a Tag
If you are creating a custom theme for Publii, you might want to list all posts with a specific tag on a dedicated page. Here's how to do it:

How to find Black&White images in Lightroom Classic?
You create a smart collection with the following settings:
Treatment > equals > Black and White
