This is almost entirely wrong. The Sherman Act has 2 sections. Section 1 prohibits actions like price fixing and bid rigging regardless of market power. It's section 2 that prohibits monopolization and requires monopoly power.

The majority of antitrust claims are brought under the Sherman Act. Apple's ebook price fixing case was brought under Section 1 of the Sherman Act.

All of Epic's federal claims against Apple are alleged violations of the Sherman Act.