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Can I view files from other users on the same local machine if I am root? If so, how?

You can $ sudo su and you're effectively a root user now.
And, Go / (root) and see /home folder can find all the user on the machine.

You can also do:

# su user

as root to become that user and see his files

Switching to a different user account from root is not safe by default.

It's much safer to directly browse into the desired directory as the root user than use su or sudo to switch users since the latter allows an infected user to automatically execute arbitrary commands as root via the TIOCSTI ioctl by pushing commands onto root's tty.

For instance, suppose there's a binary hacksu that takes advantage of the TIOCSTI ioctl and that an intruder has modified the infected user account [user]'s .bashrc to execute this binary when the shell starts.

$ tail -n3 /home/[user]/.bashrc
echo hi
/opt/hacksu -- $'echo "hello world" >> /tmp/file1nfg'
echo bye
$ _

Then, when root uses su on the infected user, the infected user gets to execute arbitrary commands as root.

root@host:~# su - [user]

The 8 following lines print themselves to the terminal without user interaction since sourcing .bashrc is automatic.

echo "hello world" >> /tmp/file
1
fg
[1]+ Stopped su - [user]
root@host:~# echo "hello world" >> /tmp/file1
root@host:~# fg
su - [user]
bye

Now, root realizes something is up and closes the [user] shell to check out what [user]'s .bashrc did.

[user]@host:~$ logout
root@host:~# ll /tmp/file1
-rw-r--r-- 1 root root 12 Apr 15 00:47 /tmp/file1 # owned by root (!)
root@host:~# cat -v /tmp/file1
hello world
root@host:~# # oops ..

In the above scenario, [user] has just written to an arbitrary file as the root user. In practice, the executed commands could do anything root could. Imagine, for instance, if the hacksu binary had been called to modify /etc/shadow instead.

The source for the POC hacksu binary can be found at https://www.halfdog.net/Security/2012/TtyPushbackPrivilegeEscalation/. Don't switch to another user as root unless you've worked around the threat of an infected user account.