1. It's so Tom. (It means a photo. There is Tom in the photo.)
2. It's Tom himself. (It means a photo. There is Tom in the photo.)
3. Winer and loser are distinguished by a small difference.

Do they look natural?

I will give you some explanation about 1, 2.
I want to make similar sentences like "He is so American."
But, I want to put [name like Tom, Sarah...] instead of [American].
I think 1 is wrong and 2 is correct.

Thanks in advance!

Question

1. It's so Tom. (It means a photo. There is Tom in the photo.)
2. It's Tom himself.  (It means a photo. There is Tom in the photo.)
3. Winer and loser are distinguished by a small difference.

Do they look natural?

I will give you some explanation about 1, 2. 
I want to make similar sentences like  "He is so American."
But, I want to put [name like Tom, Sarah...] instead of [American]. 
I think 1 is wrong and 2 is correct.

Thanks in advance!

Answer

Contect will matter.
1 - "It's so Tom." could be said if there is something a bit unique or ideosyncratic about the picture of Tom, like him doing something or dressed in some way that would be very characteristic of Tom or Tom's personality.

2 - "It's Tom himself." sounds a bit awkward to me. If you're just saying the person in the picture is really Tom and not someone else then "It is Tom." is all that is needed.

3 - That works, but small typo -- winner not winer. I think words that end in a single consonant will typically repeat the consonant before adding the "er" ending. (see https://www.yourdictionary.com/articles/suffix-spelling-rules if interested)