Yes. A Wi-Fi 6E phone, laptop, or tablet can connect to a Wi-Fi 6 router, but it will use the router’s 2.4 GHz or 5 GHz band and cannot use the 6 GHz band.
Wi-Fi 6E is not a separate technology. ASUS explains that it is based on Wi-Fi 6 and uses the same 802.11ax standard, with the E standing for Extension: it extends Wi-Fi 6 into a new 6 GHz band. Wi-Fi 6 equipment operates on 2.4 GHz and 5 GHz, while Wi-Fi 6E covers 2.4 GHz, 5 GHz, and 6 GHz. The 6 GHz band adds up to 14 extra 80 MHz channels or 7 extra 160 MHz channels, which is where Wi-Fi 6E’s gains for uses like HD streaming and VR come from. Only devices that support Wi-Fi 6E can connect to 6 GHz Wi-Fi, so getting those gains requires a Wi-Fi 6E (or newer) router as well. ASUS also notes that an existing Wi-Fi 6 or Wi-Fi 5 router cannot be upgraded to a newer Wi-Fi standard through a firmware update.
Source: ASUS Support, What Is The Difference Between WiFi 6 and WiFi 6E
Image: Modern Wi-Fi 6 router, by Pascal2187, CC BY-SA 4.0, via Wikimedia Commons.