Hi sir, unlike my other fellow bidders I will try not to bore you with generic bid.
If I understand you correctly, you have a hotel booking web application with android application, which has a php backend.
Most likely the Android app(java, kotlin) uses Rest API to communicate with the backend.
And you would like to modify or add some features to this. These features needs to be implented on the web, as php(along with the rest api) and the android app.
I can assure you I can implement your desired changes to all above mentioned layers.
Sir I would like more details like what type of modification would you like to add, to qoute you an exact price and time. Please feel free to text me if you have any quaries.
P.s. I have 5 plus years of android development(java, kotlin, react native, Twa), and 8 plus years of web development, I am new to this platform. Currently I am working on a php laravel project in freelancer and most likely my first review will be up in few days.