Yes, the RE450 can be operated in two modes: Repeater and Acces Point. In repeater mode, the retransmission of data can be prevented. This means that a bridge is only formed with the existing Ethernet port, which corresponds to the desired client mode. I have used the RE450 and also an RE650 in this way.

I can confirm Scd3044's statement. I use the RE450 in exactly the same way to have internet in my office. (Laying cables and drilling holes is difficult in a rented flat).