Sure, best way is to just start with the correct resolution. If you are doing shorts for Youtube, I would use 1080×1920 i.e. a vertical “portrait” aspect. On other social media, like Instagram, you can go with square, like 1080×1080.
So when you start your projects, make sure to go to the menu File > New Scene… and type in the preferred resolution.
If you need to change resolution on existing animation you might have done in 16:9 horizontal “landscape” aspect, you can experiment with the options in Scene Settings.
I hope this helps?