Try install php extension

I am trying to install php extension which is:-
multibyte string, mbstring, set_time_out.
But I can’t find these in cyber panel please tell me how can I install these extension in cyber panel

I believe it’s:

PHP > Install extensions > Select your version > install lsphp7*-mbstring

When you click on install, it’s give blank page. Any solution

Refresh the page.