2021 change folder permission and all its file permission

 chmod -R <permissions> <directory>

https://www.baeldung.com/linux/change-folder-and-content-permissions

chmod -R 751 folder/

After preceding command:

$ ls -ld folder 
drwxr-x--x 2 baeldung baeldung 4096 Jul 14 08:51 folder
$ ls -l file1 
-rwxr-x--x 1 baeldung baeldung 0 Jul 14 08:51 file1