If all cell are basically the same in chemical composition and metabolic activity then how do progress composed of cells have specialized function? i need answers pls!

Cells can change over time based on what is entering the system.

An abundance of a certain enzyme in an organism may cause that enzyme to bind to proteins in the cells.

Cells will also compensate different levels of chemicals in their system by changing the rate at which their cell membrane allows or rejects new chemicals. They can also change the rates of the creating new enzymes within the cell.