Starting from 2016, Apple started making a Touch Bar MacBook Pro models. The Touch Bar UI is pretty cute, but it's not practical. That's why, the Touch Bar modes come into play.
First of all, let's locate the Touch Bar customiser:
1) Open System Preferences
2) Go to Keyboard menu
1) Open System Preferences
2) Click "Keyboard" on the Sidebar
After doing all the stuff, you'll see something like this:
Now, let's click on the drop down “Touch bar shows” and select “Default set”. Also, if you want your Touch Bar to be the full size of the display, deselect the “Show Control Strip panel”.
If you want your Touch Bar to show the Function keys, select the “Function Keys” in the drop down menu.