Need suggestion to improve multi-purpose HTML template

Hello Experts,

Recently our multi-purpose HTML template get approved on theme forest but no luck with sale so we are looking for suggestion to improve that item. Please check and advise.

Here is the demo link.

Many thanks in advance.

First suggestion would be to move to bootstrap 4, I mean 3 is not viable anymore.

You item is good enough that’s why envato approved your item for sales though the sales on envato has been dropped massively.

Any planes for WordPress version ? If so I can cooperate.