The best solution = soft flooring coverings (cork or carpet) or ceiling panels. Neither one of those answer your question but it gives you an idea of where the problems lay: flooring and ceiling height.

Any chance you have to reduce acoustics by adding "soft" wall coverings, you will find a benefit. It won't be huge...but it will "help". Of course those big ceilings often come with pretty glass panels on the walls called "windows". Another "acoustic nightmare".

Acoustic challenges can be helped by using soft coverings wherever you can: walls, ceilings, drapes, carpets. All will "help". Of course the problem is MAINLY produced with hard flooring + vaulted ceilings.

Beyond rebuilding, the only thing you can do is "add" soft coverings to every thing you can think of. Area rugs, big puffy sofas, wall hangings, drapes (as thick as you can get them). If the acoustics are still a problem you may have to bring in a professional to hang acoustic panels (as seen in poorly built music theatres) or you "live" with it.

Usually once the space is filled with "stuff" the acoustics reduce more than 50%. Sofas take up HUGE amounts of echo!