Not exactly what OP was looking for, but I just found a handy solution to have the/multiple default Dropdown /Accordion element(s) opened in the Designer for easy accessibility for editing copy while in development:
Just add a custom code embed with this css rule:
<style>
.w-dropdown-list {
display: block;
}
</style>
This makes that all dropdowns are in the “open” state in the Designer. The animation that runs on page-load sets the initial state back to closed.