Hi aspirant

Definately you can go in the field in graphic designing.You can always join a course for that either online or offline.

You B.Tech degree will add value to you.So if you have decided to go for graphic designing along with b.tech ,it is one of the best decision.Even after you have done B.tech from any engineering college and you are expertise in graphich designing you will easily get internships as well as jobs.

You can join courses on Udemy,coursera,udacity ,edx and there are many more.

Hope this was helpful.