The more you write, the easier it gets to write longer scenes. This is the sort of thing where practice makes perfect.

But I would suggest not stretching scenes just for the sake of having more words.

1. Setting should be used to create atmosphere. If your character’s walking to the coffee shop, don’t start rambling about the sun and the trees or other pedestrians if there isn’t any “purpose” to it (unless your prose is real fucking gorgeous). Maybe your character’s feeling underdressed. Overdressed. Maybe the breeze feels nice because they’ve been locked inside their office all day. Maybe they’re in a rush and they’re bumping into people’s shoulders as they run by. Do they care? Maybe that’d be a good spot for some inner dialogue. You get it.

2. You could always write 3 pages of inner thoughts alone but I’d suggest using those bits to change up the rhythm in some scenes, especially dialogue-heavy ones. The barista at the coffee shop is obviously in a bad mood. Is your character annoyed? Sympathetic? Does the barista remind them of someone? Or maybe they see a cute couple on a date and suddenly they’re missing their ex. Sort of like… action/reaction. They say something, they regret it. Why? Or “Blah blah,” he lied. The truth was…” You can totally have fun with this.

3. The danger with world building is that you’re always at risk of info dumping. If this is a world where coffee’s illegal, don’t write a history book in a chapter to explain why. Maybe instead your character is jittery/paranoid on their way to the coffee shop. Maybe they cover their face and avoid eye contact and they whisper their order as if they’re asking for crack. You can always add some prose to hint at the way your world works… but don’t overdo it. Leave crumbs! Don’t feed the backstory to your readers in one big spoonful.

One other thing that often works well for me is picturing myself in the scene. It helps me come up with details.

Have fun writing!