Is it possible to write an apps script code for gsheets to check if string exists in a csv file from an external URL

So I have a URL stored in A2 cell in gsheets and would like to create a custom function using apps script for it to look something like this

=customfunction(A2,"string")

and to crawl the URL stored in A2 to search for the given string, and if found print TRUE and if there is no string in the whole CSV file write FALSE.

Is this possible ? thanks!