Some eero hardware does support power over ethernet (PoE+). To provide power to your eeros, you should use the supplied power adapter.
If you have an eero PoE+ adapter (currently only available through custom installers), an eero Pro (not the Pro 6) can be powered over Ethernet using the necessary PoE+ adapter, injector or 3 party PoE+ switch. You can review Suggested injectors and PoE+ switches. eero PoE 6 can be powered via PoE with a Cat5e cable or higher and a supported PoE switch/injector. eero 6+ power adapters are compatible with eero PoE 6 eero units.