I’m planning an essay on this subject based on video game design. You do this by adding luck to the shot.
Lots of people think luck and skill are in opposition to each other. They are not. They are independent vectors of entertainment in games. E.g.:
Bingo: high-luck, low skill
Tic-tac-toe: low-luck, low-skill
Go/Chess: low-luck, high-skill
Poker: high-luck, high-skill
Translation to golf has a lot to do with where luck happens, what type of luck you want to focus on, and how you want luck to impact results.
It’s a looooong conversation, but right now, I think prevailing winds are the best tool. To increase risk, the easiest thing I can think of is forcing players to shape shots into the wind off the tee, or bail out to an inferior position.
Shaping is an extremely difficult thing to control, and shaping into a headwind is a nightmare. Pepper some highly hazardous areas in the obvious miss zones, and you have golfers second guessing their skill on tees.