How can I reduce the number of vertices of an object with code?
For example, if an object has 10,000 vertices, I want to convert it to 5,000 vertices with code
It is not a simple task. It is easier to just create a new model in your modelling software. It still possible, though. Using Mesh API you would get all vertices and their order (indices). Then create a new positions list and the new order in which vertices connect. Here is an example of using Mesh API to create a high poly plane: