You can probably use an Open edX hosting provider for that, e.g. you can go to our hosting page at opencraft.com/hosting and click “Create Your Site” to get a temporary deployment for up to 30 days (no credit card required). Hopefully that will give you a good view of the default theme, and you can use our hosting admin portal to play around with basic customization of its colors.
the various default themes
As far as I know, there’s really only the one (default) theme that ships with Open edX. There are technically a few others but I don’t think they’re very complete or maintained. But there are some third party ones - we offer “simple theme” which is the default theme but with easier customization; there is Indigo, a new, cool blue, customizable theme for Open edX , and we (OpenCraft) are working on a substantial and exciting new open source theme for Open edX which we’re discussing in the What do you love or hate about the MOOC platforms you’ve used? thread, and developing at opencraft / dev / Open edX Theme by Opencraft · GitLab . We’d love UX ideas and contributions in that thread!