Hovered element to overflow out from an overflow:hidden element css

Unfortunately, there's no (easy) way to allow a child tag to override the effects of the overflow:hidden declaration on the parent div. See: Allow specific tag to override overflow:hidden

Your only possible recourse would be with javascript: first grab the span's offset relative to the document, then move it to another location in the DOM (i.e. direct child to the body), set its position to absolute, and use the offsets you grabbed to set its left and top properties, that would locate it at the same position within the document, but now it's not contained by the div, and so no longer needs to obey overflow:hidden.

You can use margin-top and padding-top.

padding-top will extend your parent area, but a negative margin-top will keep it in the expected position.

It will look like you're escaping the overflow, but in fact you're not.

div {
    width:500px;
    height:200px;
    background:red;
    margin: 50px;
    overflow: hidden; /* this rule */

    background-clip: content-box; /*use this to constrain the background color within the content-box and do not paint the padding */
    padding-top: 200px; /* space required to display the tooltip */
    margin-top: -150px; /*200px - 50px of the original margin*/
}
    
span {
 background: blue;
 color: white;
 position: relative;
 top:100px;  
 display:block;   
 width: 100px;  
 margin: auto;    
}
    
span:hover:after {
    content: attr(data-name); 
    color: black;
    position: absolute;
    top: -150px;;
    left: 0;   
}

<div>
<span data-name="here">hover</span>
</div>

This may introduce pointer events problems, but you can fix them using pointer-events then.