Hello,
Thanks for reaching out!
There is not an out-of-the-box way to change the opacity, but you can change some of the colors for week view under Appearance > Customize > The Events Calendar. If you want to change the opacity or if the options there do not get you the changes you need, then you would need to add some CSS. We are a bit limited in the amount of support that we can provide for customizations, but if you get stuck or have any questions, please let me know – I’ll be happy to point you in the right direction!
We do have an open feature request for a different layout option in week view. I would recommend casting your vote for it, which helps us gauge user interest in new features.
Thanks,
Jennifer