No. Zapier does not support two-way syncing between apps right now. Think of Zaps like one-way workflows.
In certain scenarios, you can fake two-way syncing by setting up two different Zaps that perform opposite actions. For instance, you could have one Zap that creates a new spreadsheet row for every new contact created and another that creates a new contact for every new spreadsheet row.
Be careful not to create a Zap Loop. Learn how to avoid Zap loops.