Installing Php7 extensions is a quite simple procedure. It looks overwhelming at first as there are a lot of extensions available to install. I can’t guide you on what extensions to install. What I can say though is, do not install more extensions than you need for security reasons. If you later need an additional extension it’s a simple make if running this installation again.
I have supplied an example here [screenshot] on what you are up against once you start the installation the extra options checked on the screenshot are for demonstration only and should be adjusted to suit your needs.
cd /usr/ports/lang/php71-extensions && make install clean
Once you selected what extensions to install go grab a drink, this will take a few minutes unless you only checked 1 extension that is.
And we are done here.