Have you ever used the search feature of the Photos app? Apple's artificial intelligence (AI) / image recognition technology automatically sets appropriate tags for photos stored in your camera roll, so words related to your subject. If you search with, you will get the photo you expected.
That's the word, but basically you can think of it. If the subject is mainly a dog, you can use "dog", and if the subject is mainly a train, you can use "train". There is a specification that seems to be a multilingual application such as "Kakigori" is x and "Frozen dessert" is ○, but if you try paraphrasing several times, you should be able to reach the desired photo.
However, if you're searching anyway, it's a good idea to start with crisp words like "animal" or "food." This is because the search function of the photo app has a mechanism to display other information such as date and shooting location as narrowing candidates along with the result.
For example, suppose you want to find a picture of a bird. You can search by "bird", but it would be convenient if you could also specify the shooting location / time. In such a case, try searching with a larger classification such as "animal". Along with the "birds" that are classified as animals, the shooting location and time should be displayed as candidates for narrowing down.
To narrow down, just tap the item. If you want to start over, click "" on the software keyboard.