Yes, you can amplify the WLAN signal with the TP-Link RE700X Wi-Fi 6 WLAN Repeater (RE700X) and establish your connection from the repeater to the PC via an Ethernet cable.

Here are the relevant details:
- The RE700X has a Gigabit Ethernet port that you can use to connect your PC with an Ethernet cable.
- The repeater supports AP (Access Point) mode, which means you can use it as a Wi-Fi access point for your wired connection. You can simply plug an Ethernet cable into the Gigabit port of the repeater and connect your PC to the amplified Wi-Fi signal.

This approach allows you to amplify the Wi-Fi signal to your PC and at the same time utilise a stable and fast connection via the Ethernet cable.