On a laptop, macOS's menu bar may be interrupted by the "camera notch" at the top middle of the screen. The space reserved for this notch by macOS is wider than it looks, and the number of icons displayed on the right side of the menu bar may exceed the available space. (This can also carry over to an external monitor that has no camera notch.) When this happens, icons will simply not appear, with no indication that they are hidden or any easy way to find them. The Palo Alto GlobalProtect icon is frequently where this is noticed, since the menu icon is the only way to access the VPN connection, but any icon can be affected.
Remove unneeded or less used icons
macOS built-in functions (wi-fi, Bluetooth, sound, battery, etc) can be added to/accessed from the Control Center, allowing you to remove them from the menu bar if they are not used very frequently. Go to System Settings, Control Center to choose which OS icons are in the Control Center and/or menu bar.
Reorganize icons
Command-click and drag on a menu bar icon to rearrange them. Cmd-click and drag off the menu bar to remove an icon from the bar entirely. You may also be able to cmd-click and drag from the empty space between the notch and the leftmost icon and "fish out" missing icons and move them towards the righthand end of the list so they are kept visible, though some icons can come and go from the menu bar causing things to move around.
Tighten up icon spacing
The icons can be displayed closer together, allowing more to fit in the available space, though at a certain point they get hard to use. The numbers listed here provide a slight tightening that is still quite usable, but you can try lower numbers.
From the Terminal, run the following two commands:
defaults -currentHost write -globalDomain NSStatusItemSpacing -int 12
defaults -currentHost write -globalDomain NSStatusItemSelectionPadding -int 8You will have to log out and back in to see the changes.
To view the currently set values for these settings:
defaults -currentHost read -globalDomain NSStatusItemSpacing
defaults -currentHost read -globalDomain NSStatusItemSelectionPaddingThe values are not set by default, so you may get an error that they do not exist.
If custom values are currently set and you want to go back to the defaults:
defaults -currentHost delete -globalDomain NSStatusItemSpacing
defaults -currentHost delete -globalDomain NSStatusItemSelectionPaddingAgain, you will need to log out & in to see the change take effect.