Is the Peerless Assassin 120 SE enough for an i5-14600K?

It is a reasonable air cooler to consider, but I wouldn't count on a guaranteed temperature below 80°C in every workload. Gaming and rendering can put different loads on the CPU, and case airflow, room temperature, fan settings and CPU power limits also affect the result.

If staying under 80°C matters more than maximizing rendering performance, check temperatures under your actual workloads and consider adjusting the CPU power limits if needed.

I'd also look at the Thermalright Phantom Spirit if you want to stick with air cooling. It's another option in the same general category, though it still won't guarantee a particular temperature in every case.

If you're open to liquid cooling, the Arctic Liquid Freezer III 280 is another option. Check that your case has room for its radiator before buying. A larger cooler may give you more thermal headroom, but the temperature target still depends on the workload and settings.

Mounting can make a difference too. An LGA 1700 contact frame may improve mounting pressure and reduce peak temperatures by a few degrees, but it's not a substitute for a suitable cooler and it isn't a guaranteed fix.