sagemaker online and offline store question

I looked at SM feature store documentation and see a flag named is_online_Enable for ingestion. My queries are -

1. If i make it false, will it only store the data in offline store ?
2. If I make it true will it store data both in online and offline store? if yes , both the store will have same data right?
3. Is there any way to store my data only in online or only in offline store ? if yes, what will be the configuration?

Also is there any scenario while ingesting data there is some syn happens between online and offline store or vice versa. I see documentation mentioning it will be available after some minutes and for our use case we want to know is there any sync happens( is there any scenario where data goes to online store first and then sync up with offline store or vice versa and some latency associated with the later store)?