In short, all you have to do is follow the instructions that I will give you in this tutorial and, you will see, you cannot go wrong. All you need is a few minutes of free time and your smartphone or PC. At this point, therefore, all that remains is for me to wish you a good reading and a good research!
Index
Then scroll through the list until you find the person you are looking for and possibly tap on theirs nominative, to see all its contents and thus be sure that it is the person you have in mind.
All you have to do is connect to Google's dedicated image search version and either upload the image or paste its URL. Then press the button Search by image, to see the result of your search (i.e. images similar or identical to the one you uploaded).
If Google's reverse image search doesn't satisfy you, consider it PimEye which, starting from 35,99 euros/month, allows you to find faces starting from a photo using Artificial Intelligence (AI).