Changing default calendar only for specific events

I use the Virgin Active app to book gym classes and these get automatically added as events in my default calendar on iPhone. This is quite inconvenient because I’d prefer them to be on a separate calendar so I can toggle it on and off when viewing all my events for the day (it gets really busy when I’m looking at work / personal events for a day). Is there any way to change the default calendar for this set of events specifically without having to go in and do it manually on every single event? Thank you so much!!