The statement "I have 9 toes" is true because they have 9 toes. If they then said "I have 10 toes", that would also be true, because they have 10 toes.
Note that I am assuming that "having a toe" means that the toe is attached to the person's body, and that I am also assuming that the person has 10 toes attached to their body. You said that the person "never lost a toe", but this point is completely irrelevant to the question because you didn't say how many toes they were born with. Were they born with 9 toes?
I met a super-hot Japanese girl from Hiroshima who has 10 toes. She was born with 12 "foot fingers" (as she called them), but her parents gave a doctor permission to cut 2 off soon after she was born.
Someone else said that "I have 9 toes" is an "imprecise statement". I agree that it is an imprecise statement, but not because the person only told you about 9 of their 10 toes.
"I have 9 toes" is an imprecise statement because the word "have" is ambiguous. Does the person "have" 9 toes attached to their body? Or do they "have" 9 toes in their fridge? etc
"I have 10 toes" is also an imprecise statement for the same reason. So since they are both "imprecise statements", this does not distinguish them and is somewhat irrelevant to the question. It does give some interesting information which is loosely related to the question, but it clearly does not clarify your confusion. I'm only mentioning it to undo the harm done by the person who said it.
Regardless of all of this jabber, the statement "I have 9 toes" is true, and the statement "I have 10 toes" would also be true, and the statement "I have 11 toes" would be false.
A statement can never be "partially" true/false. If your interpretation of the statement is unclear (which seems to be the case here), then either the terms have not clearly been defined, or you do not understand the terms.
When we see an unclear statement, we often try to make assumptions. For your question, I think most people would make the assumptions that I made: that the person has 10 toes attached to their body etc. After making assumptions about the unclear parts, the statement can only ever be either true or false.
In cases where the statement is unclear but no assumption can be made, there can be no "statement" in your mind for you to consider whether it is true or false. For example the statement "it is red", you don't know what I mean by "it", so you can't determine whether it is a true or false statement. But this does not mean the statement is not either true/false. You are only unable to determine whether it is true or false because you don't have enough information, and you can't make assumptions about unclear terms.
Note that we make many assumptions that we may not even be aware about. Your question appears to be more of a "riddle" than a question, but I am assuming it is a legitimate question and not some kind of wordplay.