Hi there,
There is not a good way to do this with Gutenberg currently unfortunately.
You can full width option in page builder container:
https://docs.generatepress.com/article/page-builder-container/
Then add HTML blocks like this:
<div class="content-container">
my content
</div>
With this CSS:
.content-container {
max-width: 1000px;
}
Or consider using our Sections add-on:
https://docs.generatepress.com/article/sections-overview/
In the future we will be introducing Sections block to make this possible with Gutenberg.
Let me know if this helps 🙂