you can get plastic spikes from online shops... i got it for anti cat to climb on my walls but the cat happy walking on them.
like one says you need to improvise, hang reflective CDs like chap fan shop

Bird Spikes: These are rows of stainless steel or plastic spikes that are harmless but prevent pigeons from landing on ledges, windowsills, and other flat surfaces. They are a very common and effective solution.

Bird Gels and Repellents: There are various gels and pastes that can be applied to surfaces. Pigeons dislike the sticky sensation on their feet and will avoid landing on the treated area. Some modern "optical gels" are designed to appear like fire to birds from a distance, deterring them visually as well.

Reflective Surfaces: Pigeons are easily spooked by bright, moving lights. Hang old CDs, reflective tape, or small mirrors to create flashing lights that will deter them.

Ultrasonic Devices: These devices emit high-frequency sounds that are irritating to pigeons but are generally inaudible to humans. They can be motion-activated to scare birds away as they approach.

Wind Chimes: The sound and movement of wind chimes can be startling to pigeons and discourage them from settling in.

Strong Scents: Pigeons dislike strong smells. Sprinkle strong spices like black pepper, chili powder, or cinnamon on ledges and roosting areas. You can also create a spray using strong-smelling essential oils like peppermint or eucalyptus oil mixed with water and a little dish soap.

Vinegar Spray: A mixture of diluted white vinegar can be sprayed on surfaces. The smell is unpleasant to pigeons and can also help with cleaning droppings.

Chili Pepper Spray: A solution of crushed chili peppers in water and vinegar can be sprayed on areas where pigeons are a problem. The capsaicin in the peppers irritates them.