I would leave them. They are very nice and they fit the area where they are. Smaller posts, will make it look less substantial. They look great the way they are.

I agree with cat_ky. Smaller pillars would look disproportionate, and redoing the whole thing including the arches would be extremely expensive without much, if any, esthetic gain.

Faux gone mad. Massively out of scale to the load (lattice top) and to the house. Looks like the support was engineered to carry stone bleachers at the Roman Coliseum.

I don't see how the load is supported close to the house...or isn't supported which may explain why the wide width.

Looks like a knockdown/ start over project. Possibly can save the top if it can come down in sections. But that approach may not be cost effective.

If the lattice top is attached to the house, it might be possible to temporarily support the roof, knock down the columns & rebuild. Temp supports like when a supporting wall in a house needs to be rebuilt. Again, maybe not cost effective.