How to merge documents and decide on any change?

Question

Let's say I'm merging two document's and some changes make conflicts and others do not. How to "merge" and be able to decide about every single change?

Doc master

<h1>hello<h1>
<h2 class="user"> sranger <h2>

Doc my_branch

<h1>helloo<h1>
<h2 class="user"> sranger <h2>
    
<script>
  let user='Miki Mouse'
  console.log(user)
  $(".user").html(user)
</script>   

This is what I expect after merging on branch master:

<h1>hello<h1>
<h2 class="user"> sranger <h2>
    
<script>
  let user='Miki Mouse'
  $(".user").html(user)
</script>

In this example it should ask me about conflict helloo - hello and if I accept every single line of the script so I could exclude console.log I'm working on VSC if it's make difference