Changing your Slack theme is a simple way to personalize your workspace, improve focus, or distinguish between multiple clients. While Slack doesn't have a traditional "download" button for themes, you can easily from community sites to transform your interface instantly. How to "Download" and Apply New Slack Themes
Because Slack themes are essentially a string of HEX color codes, you "download" them by copying these codes and pasting them into your settings. Slack Themes download slack themes