I just completed my diploma in mech engr, can I apply for BE mech engr at AIT through lateral entry? If yes what is the procedure? Please

With  percentile of 92.1 in JEE Mains and a rank of 1,17,042 you have a solid chance of getting admission into the Army Institute of Technology (AIT) for Electrical and Telecommunication Engineering, especially given their specific admission criteria for children of army personnel.

While the cut-offs can vary, AIT has its own merit list based on JEE Main scores.

Your rank is quite competitive within their admission pool. It's an excellent institute with a strong focus on discipline and academics, and your rank is well within a favorable range for securing a seat there.

No such feature is provided in AIT. You will be eligible to take direct admission in AIT if your father is Ex-Army but it's mandatory to give entrance exam and also to qualify it.

Some seats are reserved for the students whose father is in the Army or an Ex Army officer

You can likely considered to get admission into Pune via MHTCET.  AIT prioritizes children of serving or retired Army/Navy/Air Force personnel. You will need to provide a certificate to prove your grandfather's service. AIT admission is based on your All India Rank in the JEE Main exam conducted by the National Testing Agency (NTA).