We need to develop a taxi booking app which will have similar features like In-Rider application. Customer add pick and drop location, it will show estimated cost, customer add offered amount and click on book ride. The customer offered amount will go to the nearest drivers and will show them the pickup and drop off locations also. Driver than can accept on the same cost or suggest a different costs. Incase he accept, he will take ride, incase he offer a different cost, notification will go back to the end user again.
More details can be discussed but it's similar to In-Rider. Note that it's not similar to Uber or careem. Also please qoute your price, don't qoute 700$ and then negotiate for $8k.