For macOS
Take webpage. Press Command and "+" button to zoom.
For Windows
Take webpage. Press and hold Ctrl button and scroll mouse wheel up.
Edit
1) Go to System Preferences->Accessibility
2) Select Zoom and Enable "Use Keyboard shortcuts to zoom"
3) Note down the shortcuts.
4) By default ⌥-⌘-= for zoom in and ⌥-⌘-- for zoom out.