See if you are going for MSc Physics and you have plans to go for PhD in abroad then I would suggest that you should go for MSc in IIT's by qualifying IIT JAM examination. various IIT's have tie ups with foreign institute and many professors of IIT's are visiting lecturers of many foreign university. So if you have the sincerity for the subject then you will get such scope if you study there. Now if you go for PhD in premiere physics institute such as TIFR, HRI, IISc, SINP etc then you will get enough opportunity to work as a post doctoral fellow in foreign universities.

Apart from this you can go for GRE examination and on qualifying you can apply for different institutions abroad.

This are some of the ways you can follow but as per me the first two options mentioned are the easiest and linear one.

To know more about IIT JAM visit the link below:

https://university.careers360.com/articles/jam

To know more about GRE visit the link below:

https://studyabroad.careers360.com/exams/gre

I hope this answer helps. All the very best for your future endeavors!