By mistake, I copied and pasted a password into Google Chrome search box on my personal computer, a Mac computer. However, I did not press enter or click search button/magnifying glass. Is my password compromised, should I change it. Thank you.
What happens now? You should change your password.
What happened when you entered it in the Google search bar without clicking "Google Search" or Enter? Each character of text was sent (over HTTPS via GET Request) to Google which may or may not have provided suggestions on additional characters or words to enter for your search query.
You can see this live in the Chrome DevTools (press F12) as you type. Go to the "Network" tab and begin typing characters. You'll see each new character append the last request and the GET Request send off to a Google-owned IP address. You can also see the returned suggested searches in the Response tab.
Ultimately it comes down to whether you trust Google with the password you entered. In all likelihood is anything going to happen as a result of this / is your account going to be compromised? Probably not. But it is good practice to reset it given that this behavior can happen on any website you visit anyway.