How to make sites work on different versions of php?

Question

PHP

Good afternoon, actually there are old sites on wordpress, wp itself supports php7, but unfortunately not all plugins and most likely will not, but you need to start a new project already on php7, hence the question has matured how to force different Wirth. hosts on nginx use different versions of php, please tell me. Actually, Google only tells me about Apache.
Thanks for answers.

Answer 1

Docker + reverse proxying by nginx from containers.

Answer 2

An example of my bike. You will find the source there.