The toggle prop of DropdownMenuItem should control whether the parent DropdownMenu dismisses on click, but it appears to have no effect.
Demonstrative example:
import dash
import dash_bootstrap_components as dbc
app = dash.Dash(external_stylesheets=[dbc.themes.BOOTSTRAP])
app.layout = dbc.Container(
dbc.DropdownMenu(
[dbc.DropdownMenuItem(f"Item {i + 1}", toggle=False) for i in range(3)],
label="Menu",
),
className="p-5",
)
if __name__ == "__main__":
app.run_server(debug=True)