Hi,
Thanks for your query. There are two ways to do that.
Please go to this location: \pitech_quickstart_j4\language\en-GB\en-GB.tpl_pitech.ini
Open the file 'en-GB.tpl_pitech.ini' with a text editor and change your desired texts there and then save.
https://prnt.sc/26n4my5
You can change it using language override feature of Joomla also if you wish.
Please go to Extensions -> Language -> Overrides and create an override for your site language. Change this string COM_CONTENT_SUB_TITLE to change "Trending now".
Here is a sample screenshot for your ease: https://prnt.sc/26n4hmt
And another override for the underlying text 'Most', you need to deal with the string 'COM_CONTENT_TITLE'
https://prnt.sc/26n4kvo
Hope this helps!
Best Regards