Is it safe to leave Solix C1000 fully charged and plugged in?

I have a new Anker Solix C1000 for backing two appliances when the power goes out. Is it ok to leave it plugged in all the time in a state of full charge until needed?

Yes, it is safe.

It’s not generally advisable to store it this way, but it is absolutely safe to keep it plugged in, as would be the case for a UPS use case.