Hello aspirant,
It might be challenging to directly apply for a full-fledged engineering degree (B.Tech or B.E.) with your current qualifications. Most engineering courses require a science background in 10+2 (Physics, Chemistry and Maths) for admission.
These are some of the alternatives that you can go for:

Diploma in Engineering: You can pursue a diploma program in a specific engineering field (e.g., Mechanical, Civil, Electrical).  Some colleges might accept your fitter diploma for lateral entry into the second year of the program, reducing the total study time.

Bridge Courses: Some universities offer bridge courses in science for students from non-science backgrounds. Completing such a course could make you eligible for engineering entrance exams like JEE Main.

Lateral Entry into B.Sc. Courses: Explore Bachelor of Science programs with a focus on applied sciences relevant to engineering, such as Applied Physics or Applied Mathematics.  These might accept your fitter diploma for lateral entry.

Your fitter diploma is valuable and demonstrates technical skills. Consider engineering fields that could leverage your existing knowledge, such as Mechanical Engineering or Production Engineering.