Display bigger Date & Time on the screen

For iPhone: Does anyone know how to make the Date and Time always could be seen on the screen? Not just when the screen is locked. Clearly, when it's unlocked we find (only) TIME is on the top of your screen, but how can I see the DATE as well? Except I lock the screen to check it.

For Mac: How do I remain the Date and Time always on my screen, like a digital clock not only is on the menu bar on the top of the screen? I think it's too small to see. I mean what if my wallpaper is gonna be a digital clock with very good visuals.

PS: Here is a solution that would be perfect for these problems. Buy an Apple Watch!!! LOL.... But I mean even if I have one, still want this function.