You can refer this faq for multiline content in cell.

Q) How to do word-wrap (fit) content in grid cells?

Update following css in page to change cell wrapping.

<style>
.ui-jqgrid tr.jqgrow td
{
vertical-align: top;
white-space: normal !important;
padding:2px 5px;
}
</style>

Second, you can use this demo for readmore plugin.

Demo: https://www.phpgrid.org/demo/demos/integrations/readmore.php

Code: https://www.phpgrid.org/demo/demos/integrations/readmore.phps

This code works if there is only one line.

But if there are break returns (\r, \n) this code don’t work.

Is there a solution ?

I am unable to understand or generate this issue. See https://i.imgur.com/ue5O8k9.gifv

https://www.phpgrid.org/demo/demos/integrations/readmore.php