Fundamentally, Big Tech is an outsized part of what sets America's economy apart. Breaking up any of them would potentially be a footgun.
In the 1900s, Teddy Roosevelt busted up the biggest monopolies and did it boldy. He was a strong believer in capitalism and market forces, and he believed that government had a responsibility to keep market forces working well.
I know we are not in the early 1900s anymore, but I think it is interesting to ponder how the only politicians who dare to say something similar today are the furthest left we can imagine (Bernie Sanders and AOC and the like).
We still have the antitrust laws of Teddy Roosevelt's era, the Clayton Act and the 1890 Sherman Act.
Sherman Act, Section 2:
"Every person who shall monopolize, or attempt to monopolize, or combine or conspire with any other person or persons, to monopolize any part of the trade or commerce among the several States, or with foreign nations, shall be deemed guilty of a felony."
The US Justice Department hasn't often applied that standard rigorously, but it can if it wants to.
Also thankfully general regulatory situation (and arguable level corruption) isn't as quite yet as bad as it was back in the 1900s.