I don't use One UI Home, (I use Nova Launcher), but it should be: Go to Settings > Accessibility > Display size & text, and then increase the font size slider to your preferred level. You can also explore specific widget customization options within the widget itself for further adjustments.
You could also install the Home Up app within the Good Lock package. There is an option, depending of how many rows and columns you have as grid for your home screen, to make your widgets font bigger.
