The code below was copied from Bootstrap5 site but the dropdown does not work in theBlazor Web App standard project created with:
Interactive render mode:Server
Interactivity location: Global
It uses @rendermode InteractiveServer on required pages.
<nav class="navbar navbar-expand-lg navbar-light bg-light"><div class="container-fluid"><a class="navbar-brand" href="#">Navbar</a><button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation"><span class="navbar-toggler-icon"></span></button><div class="collapse navbar-collapse" id="navbarSupportedContent"><ul class="navbar-nav me-auto mb-2 mb-lg-0"><li class="nav-item"><a class="nav-link active" aria-current="page" href="#">Home</a></li><li class="nav-item"><a class="nav-link" href="#">Link</a></li><li class="nav-item dropdown"><a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false"> Dropdown</a><ul class="dropdown-menu" aria-labelledby="navbarDropdown"><li><a class="dropdown-item" href="#">Action</a></li><li><a class="dropdown-item" href="#">Another action</a></li><li><hr class="dropdown-divider"></li><li><a class="dropdown-item" href="#">Something else here</a></li></ul></li><li class="nav-item"><a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a></li></ul><form class="d-flex"><input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"><button class="btn btn-outline-success" type="submit">Search</button></form></div></div></nav>