It's too often that animation filmmakers tackle aging with a wink and a nod, a song and dance to signify passing time, or keep it out of the main course of the plot, before and afters thrown in to get "miracle of birth" mileage. And worse yet, it's one birth to another, or birth to marriage. It's yet another unwritten rule to widely be considered "good" animation.
So what are some examples?
One example is Son of the White Mare. You see the main character from conception, with brief but effective moments until he's of age, and it helps bring you into the story.
Then there's Toei's The Wild Swans, where Eliza is shown over the course of years, weaving to save her brothers at the neglect of her personal well being. It adds needed emotional weight to a film with such stock characters.
The Fox and the Hound obeys the birth to marriage trend, but it adds a bit on the way, largely due to its literary pedigree. Tod and Copper are seen from inception to adult age, with attention to them both at many places along the way. It even takes an interesting turn at the end with Tod transitioning to the forest, which gives the process more dramatic character.
Karel Zeman uses aging quite brilliantly in Krabat, focusing on time as the students progress, only to be beaten down by the head wizard. The use of time makes the film interesting, with the main character young but not quite as young as before. The shapeshifting, time, and urgency of the characters make the film interesting, as does Krabat's gradual change within the hierarchy of the wizard's school.
That's about all I plan to post for tonight, though I may add more later. As a final unrelated note, I actually watched Sudsakorn part way through and found it to be filled with ridiculous errors in animation. I really was a bit too impulsive, and now I see why the film hasn't gained much recognition.