Redirect to different domain also force http to https

Are you using separate VS for port 80 and another VS for 443 ? If so, you can use something like this:

when HTTP_REQUEST {
HTTP::redirect "https://c[HTTP::uri]"
}

I am assuming that VS1:80 is for handling the 3 domains ONLY i.e., no other domain relies on that VS1:80. If you have multiple domains relying on VS1:80, you can use something like this:

when HTTP_REQUEST {
switch -glob [HTTP::host] {
"a" -
"b" -
"c" { HTTP::redirect "https://c[HTTP::uri]" }
}

Although you end up with 2 VS, I think this is a cleaner way to configure the F5 and it effectively restricts access to port 80 & 443 on the VS.