Hi Gokul Ganesh,

Yes you can join Indian army after completion of BTech and MTech. There are several entry routes available for engineering graduates, including the Technical Graduate Course (TGC), Short Service Commission (SSC-Tech), UES(University Entry Scheme), CDS(Combined Defence Services).

• All eligible male engineering graduates can apply for TGC entry, later Indian army decides the cut off percentage and shortlist the candidates out of all applicants. So at the time of applying, there is no percentage criteria.
• UES entry known as University Entry Scheme, this is also similar to TGC and SSC tech but only final and pre final male engineering graduates are eligible for this entry.
• CDS is another popular entry if you want to join IMA or OTA. This entry is conducted by UPSC twice every year for both male and female candidates. You need to pass written test first to attend SSB interview. Any graduate can apply for this.
• SSC(short service commission) is also an option where the candidates will be trained in OTA 60% candidates opt for permanent commission in SSC.

For more elaboration you can refer to this below attached link. https://www.careers360.com/careers/career-in-defence-after-engineering

I hope this helps.