You can follow this instruction to make dropdown menu of Shopify Dawn theme and other free 2.0 Shopify's themes open on hover instead of clicking menu. Please follow these steps.
Login to your Shopify store
Online store > Themes > Edit code
Open theme.liquid file, copy and paste this code below before </body> element and save the file.
<script>
const inlineMenu = document.querySelector(".header__inline-menu");
const detailsItems = inlineMenu.querySelectorAll("details");
detailsItems.forEach(item => {
const ulElement = item.querySelector("ul");
item.addEventListener("mouseover", () => {
item.setAttribute("open", true);
ulElement.addEventListener("mouseleave", () => {
item.removeAttribute("open");
});
item.addEventListener("mouseleave", () => {
item.removeAttribute("open");
});
});
});
</script>
You are done. Open your store and check how it works now
I hope you are enjoying!