I can answer this from personal experience. I scored a measly 54.83% in my 12th. Got through a really good engineering college in Pune (top 40 nationally) through NRI quota (go search it up, it exists in most univs, private or government), did my engineering with distinction and then did my MBA from a top 20 institute nationally (merit, was among the top 2–3% across many national tests).
Did I face any trouble along the way for my 12th score? Yes. During my MBA placements (I did not sit for engineering placements). I was rejected at screening stage by a multitude of companies who judged me by my score of 6 years ago. However, I eventually got into the stream of my choice purely basis my drive and caliber and am doing pretty well today compared to those who scored 80 and 90% in my batch.
Long story short, don’t worry about your marks so much. If you want to take a drop, take one. But make sure you make the year count. If you want to go ahead and take admission in an engineering college, go ahead. But make sure you ace what you do.
Life is too long and far too exciting to be bogged down by one score. Give yourself a kick and make sure you never repeat your 12th standard score in your life 🙂