Is it possible to set touch bar in F1-F12 mode for a specific app?
Yes:
System Preferences -> Keyboard -> Shortcuts
Select "Function Keys" and hit the plus sign.
Select the app you want to have the function keys display for as default.
Yes:
System Preferences -> Keyboard -> Shortcuts
Select "Function Keys" and hit the plus sign.
Select the app you want to have the function keys display for as default.