One thought I had was to go a very cold place and freeze CO₂ out of the air, about -80°C.

There’s the katabatic winds off of the glaciers in Greenland and Antarctica, which could help things go through.

But I soon realised that CO₂ is so potent, that it’s so such a small proportion of the air that not much would be taken out.

There’s some renewable storage systems that liquify air, that could remove CO₂ but they don’t mention it;,but air liquification doesn’t seem to be growing fast as an option.

The other one from mere A-level chemistry is buffer solutions and using chemical reactions in the Oceans, apart from iron seeding for life, but a chemical that precipitate an insoluble carbonate. Not ideal raining down precipitates, or using the Ocean as a test tube.