Is there a way to change "Mail alias mode for alias domains" to "Copy aliases from target" to "Catchall forwarding" for all existing the domains on server in order to avoid bounce mails?

i don't know.
however you can set your mail server to reject instead of bounce.
bounce is not a good policy. reject is.

bounce, mail comes in, finds no recipient and sends it back.
reject, mailservers talk to each other, if there is some issue on the receiving end, mail is not send until that issue is resolved.

an issue can be no recipient, mailbox full etc.

in my opinion setting catch all means also receiving spam and have no control on what happens on your server.