The short answer is both No, and It Depends.
It’s almost never a good idea to store passwords in plain text, especially in a web accessible location, if for no other reason than a simple server misconfiguration or an echo in the wrong place could expose it to the world.
If you MUST store a password, (which is possible) you could try to store it outside the webroot, eg
/var/www/public_html/ Put your codez here
/var/www/includes/ Put your passwords here
Even better than that would be to have the system that you need the password for (eg a database wrapper ) return an object already instantiated. so rather than asking for $databasepassword you ask for a PDO object, and store your database classes outside the webroot.
The It Depends comes from what attack vectors would cause someone to have access to that password text, and would it require them to be already inside your filesystem, if so, you’re probably screwed anyway.
Also, if its the password to your supa-secrit subscriber content, meh, all you’ve lost is some subscription fees, if its your database, you may have a problem, if it’s your online banking details, um good for you.
How valuable is the thing the password is protecting?