Is there a Wordpress "functions.php" equivalent in antimatter theme?

I'd like to enable pinch zooming in antimatter and read in a post that I can edit the templates/partials/base.html.twig file viewport settings to do so. However when antimatter is updated, will I lose these edits? In wordpress there's a functions.php file for most themes that is a safe place to put custom functions and such, is there something like this for antimatter?

Have a look at Theme Inheritance in the documentation. I think it describes what you want to know.

Do not directly modify a theme. functions.php in WP as far as I know is a place to put custom PHP code for the theme, but it's going to be overwritten if you update the theme. Same works in Grav. If you update Antimatter, it will overwrite your changes.

As @bleutzinn mentioned, create a child theme and put your edits there.

Thanks, that's what I'm looking for! I'm really digging the simplicity of the system and the way I'm not forced into a box.

Nice, the Them Inheritance page was exactly what I needed and now the child theme is working perfectly to remove the zoom blocking.

Question- I've lost the menu dropdowns. I recall that antimatter had a theme option to turn those on. How would I get my child theme to not override the antimatter dropdown setting?

Never mind- adding

dropdown:
enabled: false

to the mytheme.yaml file turned it back on.