Read to me uses the voices installed on your device. Many devices can add clearer, more natural voices for free:
iPhone / iPad: Settings → Accessibility → Spoken Content → Voices → English. Download a voice marked Enhanced or Premium, then pick it here.
Mac: System Settings → Accessibility → Spoken Content → System voice → Manage Voices. Download an Enhanced or Premium voice.
Windows: in Microsoft Edge, voices named “Online (Natural)” are usually available here (they need a connection). Windows Settings → Time & language → Speech can add more voices.
Android: Settings → search “text-to-speech” → choose Speech Services by Google → Install voice data → English. Reload this page afterwards.
Chromebook: Settings → Accessibility → Text-to-speech → Speech engine / voice settings, and add Google voices where offered.
Voice names and menus vary by device and version. A new voice can appear here only after the page is reloaded.