Do case study using rest api. you can just start building the basic apis and add validations you need. You get time to do it and it is offline. It not very hard.

The online assessment consists of dsa and core cs fundamentals . The level of dsa questions can vary from moderate to hard. There are 2 technical interviews. Round 1 is mainly dsa level moderate and round 2 revolves around system design, devops and maybe dsa. After these there is only hr round