How does the new worker look? in this sentence, is it okay to use new worker?

Yes, “new worker” is understandable and grammatically okay in that sentence, but it can sound a little unnatural depending on what you mean. If you mean someone who recently started a job, “new employee” , “new hire” , or “new coworker” usually sounds more natural.

Better options

• “How does the new employee look?”
• “How does the new hire look?”
• “How does the new coworker look?”

When “new worker” works

• It works if you mean a worker who is newly hired in a general sense.
• It sounds more natural in workplace or safety contexts than in casual conversation.

Small style note

If you are asking about appearance, “look” is fine, but in some contexts “How does the new worker seem?” or “What’s the new worker like?” may sound more natural.

TL;DR: “new worker” is okay, but “new employee” or “new hire” sounds more natural.