If you tell me your exact phone model (e.g., Pixel 7, Galaxy S23, iPhone 14), I can give you the precise steps.
Android devices offer more flexibility. Most modern Android phones allow you to adjust a "Grid Size," which changes how many icons fit on the screen. More icons per row/column = smaller icons. how to make icons on home screen smaller
Most Android launchers let you resize icons: If you tell me your exact phone model (e