Hi Sanjeev Nayak and welcome to the QnA forum
In the following link you can get the list of Azure SQL Database and Azure Synapse Analytics Gateway IP addresses
With that said, here is a good tip for these who can control the firewall and need to open it for specific IP for one-time-use (I am using this trick a lot especially during lectures in events):
Try to connect -> get the exact error and get the specific IP which you have for your service right now (this IP can be changed but it is what is used now) -> and open only this specific IP for better security
I hope that this covers you needs :-)