The “enable secure erase†button does not actually erase your device. Instead, what it does is reach out to the device to and turn on the Device Admin permission for the Find My Device app. So if that's all you've done, your data is still fine, and you can undo it by going into settings and removing Device Admin permission. Despite that, I'd still go with acejavelin's paranoid approach if I had any un-backed-up data.
After you press "enable secure erase", Google contacts your device to enable the feature (not erase your device) and once Google gets an answer back, you should see two new buttons — "lock device" and "erase device". If you then hit "erase device", your device will be erased. And since it was probably online (otherwise the two buttons wouldn't have appeared), it's very likely too late — the device has already been erased.
Google does make it very clear what this button does:
Unless you pressed that button, you should be fine — but again, there is no harm in following acejavelin's paranoid procedure, so I recommend being paranoid!