Is agent 247 right about cengage?

Samajhdar ko ishara kafi hai. You guys know whom I'm talking about... I just want to know whether somone actually made it into IIT Delhi or any other iit just by cengage? I'm in 12th, and tbh, staying in school and preparing for jee was worst decision of my life. JEE mains April attempt is my Target along with boards. (My mom's principal, so I cannot say that I dislike xyz teacher because the teacher literally knows me since 6th grade)... I have bought a cengage 1 jee mains all in one book for physics for 500 rs for numerical problems for boards and I'm pretty satisfied with it (except capacitance chapter, backchodi pel rakhi hai bas) Language is clear to me and I usually solve 60-70% of the questions after illustrations. I feel that I cannot make past 98%tile. Though with state reservation, I can probably get into NIT Hamirpur. I'm wondering whether buying cengage for maths+ Physics Galaxy+ N awasthi+ MS chouhan is the right combo for a drop year ... I want to get into mechanical engineering at iit Delhi, not really interested in CS Also: my parents want me to go to TUM in Germany... Is this better option than IIT?