Can opening a new credit card lower my score?

According to myFICO, new credit determines 10% of your FICO Score.
In your case, opening a new credit card account may not affect you much. But it may harm your score if you do not have a long credit history and open several credit accounts within a short period of time.

Yes, it may affect your credit score.

If you have a short credit history, then I would suggest you to not apply for too many credit cards within a short period of time.

It isn't true that your credit score will drop after opening a new credit. However, if you don't make too many charges on your new card, then your credit score will gradually go up.

Your credit score may drop by about 7 points after opening a new credit card.