No you don't need.
If you fetch from a relay a "kind 10002" of an npub you obtain the relays that npub is using.
This is an example using "nak" with my npub
./nak req -k 10002 -a dc1be7fdba0c8a1bf9065cdee45c948d574e780f74894251e9c95d16432655b9 wss://nos.lol | jq
connecting to wss://nos.lol... ok.
...