Consider that the federal government collected revenues of $3.5 trillion in 2019, or more than $10,000 for every person in the country. State revenues combined were more than $1 trillion in 2019, for a total average tax liability of about $13,600 per-capita. I don't see a realistic way to double or triple that revenue number while taxing income alone (and citizens would naturally demand a commensurate increase in government services if such a tax increase applied at lower-income levels).
Taxing wealth or ownership in companies is another route, but individuals who own any notable percentage of a public company are naturally very mobile, and could easily change their country of residence to somewhere more tax-friendly (like former Google CEO Eric Schmidt may be planning).
It seems like a difficult position to be in for the government.