Hi Harshika2305.
Plenty of people start at relatively low GMAT scores and achieve large increases.
For example, GMAT Club user dcummins recently scored 710, and he started at 430.
https://gmatclub.com/forum/from-430-to- ... 13804.htmlI also know a non-native English speaker who started at 380 and ended up scoring 750, with 47 in verbal.
So, the idea that your score would not increase more than 100 to 150 points is just not correct. With effective approaches and sufficient work, you can make your score increase as much as you want it to increase.
That said, driving a GMAT score higher can take a lot of work, and driving a GMAT score 300 points higher generally takes a lot of organized work that involves starting by learning the foundational concepts necessary for answering GMAT questions, progressing to learning how to apply those concepts in answering GMAT questions, and carefully answering hundreds of GMAT questions to master arriving at correct answers.
In doing that type of work, you would probably achieve results much more readily if you were to use a self-study course that lays the work out for you, helps you to track your progress, and provides plenty of practice questions. For quant, as user cantaffordname suggested,
Target Test Prep would be a great option. You can try the course for $1. So, take a look.