Prevent apps from storing passwords in keychain

Open safari and its preferences > Autofill > uncheck the box of users name and password , so that it will not fill up in user library > keychain folder , for third party apps ( generally avoided to be installed in Mac ) if they are to be installed , if an option appears to add password click on not now .

No. That is under the program's control. Where else do you want them stored? Is there something wrong with the Keychain? Of course, you can use a password manager but entry may be manual. Still, the actual password is also going to be stored in the Keychain.