Nowadays, I observed that most engineering graduated are left without getting jobs or end up getting non-relevant jobs. The Educational Institutions on one side and companies on the other side are not thinking about the career growth of students, but looking only at their own business growth.
I myself an engineering graduate (ECE branch) passed out in 2017. But now I'm working as an SEO Analyst. So, the conclusion is that "You can start your career in SEO, being a B.Tech fresher".
The justification for my statement: (The reason why I advise or suggest to go for SEO or Digital Marketing field)
Currently, most of us use the internet for some or other reasons. (whether it can be watching youtube, reading a blog, watching movies online, money transactions, etc.) It means people consume and spends most of their daily time online. Therefore the more the internet is being used, the more scope or demand the digital marketing has! Hence, you can confidently step into digital marketing as an SEO.
Digital marketing basically consists of several components namely SEO (Search Engine Optimization), SEM (Search Engine Marketing), SMM (Social Media Marketing), Email Marketing, Inbound Marketing, etc. as major components. Since your question is about SEO, I will only speak about it.
SEO is one of the very very important parts of Digital Marketing. So, it will never die and is an evergreen digital strategy for any kind of businesses. I can assure that it exists as long as the search engines like Google, Bing, etc. exists. SEO is all about ranking any websites on top of SERP's (Search Engine Result Pages) and thereby bringing more traffic (Users) to the website.
Coming to training. You can get trained in 2 different ways.
1. You can learn it completely by yourself for free using the internet. With 1+ years of experience in this field, I can confidently tell that everything about digital marketing you can get or learn from the internet. But with few conditions: you should be dedicated, passionate and willing to spend more time to research and learn a lot. So, this process will take a little longer time and it is completely FREE!!
2. The second method is by joining any training institution. By doing this you can learn it fast but you should put enough efforts. Some of the popular and well-known training institutions are DigitalVidya, DigitalKora, DigitalDeepak, etc.
Conclusion: If you want to save time, go for training institutions. If you want to save money, learn by your self. I believe you can learn a lot by learning it yourself instead of getting trained by someone else, but choose this only if you have time.