Notes

The Sims 4 City Decade Challenge 2021
Note: This is a challenge that i made up for first-time players.
Part 1; Getting Started
Firstly, move your sims into a city or village that you have not visited before. For first-time players, make a sim in CAS and choose a city or village [the first sims have to be young adult or adult] and find someone to be partners with. If you have brought a expansion pack which comes with a new city or village that you have not seen before, go to it.
Part 2; Basics
Start residing sims there. This is like a Decade Challenge. First, use computers which give a 90s or 80s look. Start in the year 1983, then go up to the current year. For seasons, only add them in if you want to make years come after the season. Also, to add them in you will need a expansion pack called "Seasons" which adds weather and seasons into the game. With the base game, there are actually no seasons in it so to get to the next year, you would have to rely on skipping to the next year. Use CC for the stuff you need if you meet the requirements to install the mod. Mostly download mods which include masks and COVID-19 sickness mods when you get to 2020. Use mods which gives a 90s computer style too. [You don't need to skip to 2020 if you do not like your sims being sick]
Part 3; First 2 Decades [1983-1999]
For these decades, you will have to get retro 80s style and retro 90s style mods for some stuff. You are fine with using phones, but only use '"wall-mounted" phones or else it will either look too vintage or look too modern. For kids, you may want to get mods which unlock toys which existed in the 80s or 90s with the logo layout at the time.
Part 4; Decades 3 and 4 [2000-2019]
By the time, computers began changing. You are now able to purchase non-vintage products. Giant changes go around the whole city. This may be the best decades to host parties in the city. It was only 20 years until coronavirus became uncommon in people when 2000 came, and there was lots of time to hang around in the city before coronavirus was more popular.
Part 3; Decade 5 [FINAL DECADE] [2020-2023]
By this time, when you first start the decade, get coronavirus mods and other stuff and add COVID-19 sickness mods. Do not let people enter stores or other places [unless it is a shop] but for places which are shops, you must wear masks. Do not host events. Make the kids do home school [this requires a mod] until the end of 2020. By 2021, you can make your sims go in the shops, but wear a face mask all the time when entering other places. By 2023, make corona end.
Now you can have freedom and do whatever you want after passing 2023. You can choose to quit the challenge or restart it all over again.