Correct, or get the 433 MHz Other Areas version of the WH51 if you already have a 433 MHZ LilyGo. Either way, the frequencies should match.
This is the general concept, and while I do not have a WH51 myself, it seems to work fine for others here in the forum. If you do ge the 868MHz version/LilyGo, you’ll likely also have to fine tune the frequency in the WebUI to 868.35 MHZ for proper reception …