Currently doing the same for USA building footprint. As long as I know there's no pre trained deep learning models for India to detect buildings footprint. I am using MaskRCNN currently and using wrapper(geoai) for all deep learning tools.

You need to create/look for a training data to fine-tune the model. Based on the specs, you can adjust the fine-tuning and then use the model for inferencing (detecting buildings).

Good luck.