Hi Pragya,
To earn Microsoft Certified: Azure Solutions Architect Expert certification, you need to pass both AZ-104 and AZ-305. Since you have already been working with Azure, I suggest you start by going through the AZ-900 learning collection to brush up on foundational information, then proceed on to AZ-104 learning collection to start preparing for exam. There are free assessments you can take on the exam pages to test your knowledge and help you prepare.
In addition to above, AZ-204 is excellent exam as well in terms of improving Azure knowledge/understanding, but you don't need it to earn Solutions Architect certification. From knowledge standpoint, it's good for architect to have though, and some of it will be easier for you with your background.
Please click Accept Answer and upvote if the above was helpful.
Thanks.
-TP