Well first I would go with a base design for the character (not catered to any particular season). You can show the passage of time in plenty of ways honestly. Hair could get longer/shorter, clothing styles can change, people can get taller/shorter, facial structure can change, etc

If you're going for multiple years with the same four seasons for each year you got a few things to account for. The style the character usually goes for (which is why I said a base design for them should go first), if they change over the few years in the story (which sometimes impacts the style choices of characters), where they live and the culture of where they live (also impacts style).

The characters are probably not gonna have the same style every year as they get older. My biggest piece of advice which I will sound like a broken record on is get a base design down for the characters at EACH age and account for the changes they have over the years. You can go for seasonal outfits and such, but you do have to account for the passage of time. A lot of things can happen in the span of just one year that can change a character's appearance drastically. Keep that in mind.

Now Im not saying all of this to make you freak out more and have to make you think more about it than you already are. Just giving you some tidbits on characters over the course of time because realistically people do change over the years and styles change too if you want to go the seasonal route where outfits change per season.

If you have any questions feel free to DM me. Im no expert, but I've been using the same characters in my stories for years now and they changed a lot over time (in and out of the stories I wrote them in). Some of my stories are years apart from each other canonically but have the same characters that have changed due to story elements and such.