Copy Paste a Web Page and Complete te

Which is recommend best and simplest way in Word Press for:

1) Copy my the entire site (design, look and feel, menus, all 100% files) and then paste in another domain eg from to (Is Shipper plugin what can help me with this)

2) Same question but only for a single page. For some sites I have Divi which make simpler (just to download jsonfile), but other WP I have other builders or none at all. So is there a way to copy a single page design (one page id or url) and then upload it in a different site?

3) Also is there a way to copy third party site (or one page only) without accessing their WP Admin. For instance accessing html code.