Can I use CentOS 8 for Asghar Ghori's book for RHCSA 8?
 

https://amzn.to/2AJJnor
As Red Hat is available for free only for a limited duration.

Centos is identical to RHEL, apart from artwork and licensing. See also https://www.centos.org/about/.

TLDR yes.

@ silvercointyro,
I can recommend this book. I am studying after it also. Initially I started with online documentation but my eyes would heart from watching the laptop screen for so many hours. The book is very well explained and has theory, examples and exercises + 4 x sample exams. My level before the book was cd, ls, ps -ef, ping and ip a. Now I am confident for all the objectives in the exam.
But I suggest to follow also Sander v Vugt videos (maybe to pay some subscription from 3rd party vendor - not RedHat). And maybe some Youtube videos but in this case not all of them are done by professionals.
Note that the 2nd edition of this book had been published, contains containers and scripting.

@OP. What do you mean "available for limited duration"? You can renew your 12-month no-cost Red Hat Developer Subscription after it expires. As many times as you want.

Is it still available. I tried opening the link but could.t reach it. Any leads?

CentOS 8 has become CentOS stream. It is no longer a clone of RHEL but more sort of a RHEL testing, for lack of a better term.

You might want to take a look at ALMA Linux. It's more like what CentOS used to be. I've been experimenting with it in a VM for some time and it seems to work quite nicely.