Crazy Ideas

It's basically a fact that companies that make their office desirably to be at in general get better attendance. Cheap food, good culture, good facilities all contribute. Even then, if you're at a shitty flex desk most people would much rather the comfort of their own desk, screens, peripherals. I think a huge amount of companies underinvest in this area. You have to make working from the office genuinely more enticing than working from home and one of the biggest factors here is costs. It takes an epic culture to override that cost imperative.

From the culture side:

Run events to draw people into the office. I organise takeaway once a week and it sucks heaps of people into the office for a good lunch, but really the business should facilitate that or comp it even because I've clearly proven it gets people in the office and motivated.

Design the office for collaboration, prioritise mobility so the office can be restructured for the work at hand. Minimise underused desks. I work in engineering so relocating to other desks is a huge pain when you have to bring all your hardware with you (power supplies, debuggers, oscilloscopes, programming jigs etc.) I wish my business had rolling desks or some kind of nice system for allowing these setups to move quickly and easily.

From the cost perspective:

Free or very cheap food is a huge huge perk. People hate packing and prepping a lunch in advance but it's almost always cheaper to do that or just work from home.

Free laundry is a great suggestion, save energy and water bills by doing it at the office. On-site gyms are a great incentive if they can cater to the demand because a gym membership costs a ridiculous amount.

Free EV fast charging is basically free fuel, helps cut back on that commuting cost. Or alternatively supplement public transit expenses, ebikes or even car service costs.

I'd even pitch giving employees a budget to get their own screens, keyboard, mouse etc if they make an effort to come in often enough.

Whatever it is, the more a business goes out of its way to make the office a cool place to be, and not cost more to be at than home, the more people will attend.