Story progression...

Hi @RonneeSimmer 🙌. Lol I'm the opposite, I don't want my NPC's doing any of that autonomously xD. I won't even let the game autonomously fill empty homes! When I do want some of them to get married, move to a new home, have children, etc., I just do that in Manage Households. I use the cas.fulleditmode cheat for if I want to tweak things on an existing Sim while I'm in there. It's not a true story progression mode but it's fairly quick and easy and I like having the extra control. I'm sure someone else can suggest something better but this is how I do it.

Have fun & take care!

Unlike you @RandomBuzziness, I have used mods to let NPC-s have kids. The problem stays the same. You have to go there once in a while to age up the babies, toddlers and kids. That is to say; in the gameplay that I am quite fond of and used to. [Admin - removed] So , at a certain moment I had a couple of the babies removed for adoption. No way that would happen in my households. I do tend to use the option: 'fill empty homes'. If i do not like the family i just evict them and move them out of the game in the 'Manage Households' option.

Back to you, @RonneeSimmer. To be honest, I have never heard of cheating NPC-s in having babies, or for that matter have pregnancies. There are, however, a couple of mods that can do the trick. Of course MCCC is best used for creating any type of offspring. But since you don't want to use them there is not much left than visit these families once and a while and create your own with the option RandomBuzziness gave you.
Have fun gaming!

@Trismagistos I've never used mods and I don't wish too. I don't like them. Thanks though.

@RandomBuzziness What does the cas.fulleditmode cheat do exactly? I haven't used that one before.

@RonneeSimmer It enables full CAS editing for existing Sims and Households, just like as if you were creating them new. This includes things like age, traits, and household relationships that are normally locked out for existing Sims.

So if I wanted to do something in Manage Households like age-up Cassandra Goth and Malcolm Landgraab to young adults, custom pick their new traits, move them into a new family home, and change their relationship to married, I would need to enable this cheat first. I could also so something like age-up Alexander Goth to teenager and pick his new trait while I'm in there.

It's still not a true story progression like you are looking for but it does allow you to have more NPC marriages and families in your game without having to do it through game-play. It's one of the official cheats released by Electronic Arts and not a mod in any way.

https://simsvip.com/sims-4-cheats-codes/

Make sure to enter the cheat before you open a Sim or Household in CAS for the cheat to be properly enabled. It's automatically disabled when you exit the game. I suggest playing around with it in a test save before using it in any legacy saves you might have, just until you get the hang of it.

I hope this helps! Good luck & have fun ;-D