Changing desktop icon size in Ubuntu 19.04

I just went from 18.10 to 19.04 and the desktop icons and shortcuts are there but they are too large.
Previously I could decrease their size from nautilus but now they seem to not respond to that and as far as I know, the desktop icons are no longer under nautilus.

I was wondering if there is a way to decrease the size of the icons already on my desktop instead of installing some new extension to create new icons and then resize them.

Indeed, desktop ions are not anymore provided by nautilus. They are now provided by a Gnome Shell Extension. The icons can be resized, but the options are limited to some preset sizes and are currently not exposed in the default user interface.

Using Tweaks - The easiest way to change the icon size is to install Gnome Tweaks (aka "Tweaks"). On the "Extensions" tab of Tweaks, you will see a cog next to the "Desktop icons" extension. Click the cog to access configuration options for the extension, which include a choice between "Small", "Standard" and "Large" desktop icons.

Using the terminal - Alternatively, you can control the size with a terminal command:

gsettings get org.gnome.shell.extensions.desktop-icons icon-size 'standard'

Other possibilities instead of 'standard' are 'small' and 'large' You can learn this with the command

gsettings range org.gnome.shell.extensions.desktop-icons icon-size

To reset to default:

gsettings reset org.gnome.shell.extensions.desktop-icons icon-size

Customize icon size - For advanced users only

Only three preset icon sizes are available in the extension's preferences. Customizing these sizes unfortunately requires hacking the source code of the extension because icon size presets are hard-coded in the file prefs.js.

const ICON_SIZE = { 'small': 48, 'standard': 64, 'large': 96 };
const ICON_WIDTH = { 'small': 120, 'standard': 128, 'large': 128 };
const ICON_HEIGHT = { 'small': 98, 'standard': 114, 'large': 146 };

The system wide extension is installed in /usr/share/gnome-shell/extensions/desktop-icons@csoriano.