how mac OS in photoshop in alt button presswith active menu bar option

If Ged_Traynor has interpreted your question correctly so you’re asking about keyboard access to menus in macOS, then you will find the keyboard shortcuts you need in this Apple help article, scroll down to “Keyboard focus shortcuts.” This is not a Photoshop feature, it’s a macOS feature.

https://support.apple.com/en-us/102650

So, for example, if you want to choose a menu command that does not have a keyboard shortcut:

1. Press Control-F2. That moves focus to the menu.
2. Press arrow keys to choose the menu, then press spacebar or down arrow to drop the menu.
3. Type the first few letters of the command you want. As soon as it’s matched, you can stop typing. (Unlike Windows, you don’t have to memorize what to press with Alt, all you need to know is the first word of the command you want.)
4. Press spacebar or Enter to choose the command.

In the demo below, I do not touch the mouse, I use only the keyboard.