See in India for studying MBBS one need to appear for NEET examination which comprises of three subjects Physics, Chemistry & Biology of 11th & 12th level. Now if you wish to build a very strong foundation for NEET from Grade 7,then you can go for the different foundation courses offered by top coaching institutes such as AAKASH, Allen etc but this starts from Grade 8 only. Apart from this there are foundation books such as Disha Series Foundation series for NEET is a very good book for the students, which you can find in any of the online shopping platforms.

I hope this helps. Have a great eve!