How to disable DNS in Samsung Tablet X's Android

There's some reason you're asking this question.

Describe the exact problem you're trying to resolve by disabling DNS.

Likely there's some other approach to provide you a solution.

There's only 5 URLs (our company's websites) that we want the tablet users to access via Internet
using Chrome & unfortunately our IT Developmt team don't plan to develop mobile apps for these
5 URLs.

>As many sites use rotating reverse proxies or dynamic DNS, this is not practical
The 5 URLs don't use reverse/rotating proxies nor dynamic DNS, so it's still feasible

These tablets can't be controlled using our corporate MDM.  Have also tried some apps
like BlockSites but it only block a few categories (like shopping, entertainment, porn &
even its subscription based apps don't completely block some malware-linked sites
like gooddrama, kissasian (a number of our users/customers favorite pastimes is to
watch movies & these sites are known to cause frequent infections).

Thus my idea is to code only 5 IPs in hosts & stop everything else.  I've tried out
kaspersky, Trendmicro etc but none of the firewalls does this thing of "Block All,
permit only the few"

https://www.androidpolice.com/2020/03/26/make-android-use-dns-server-choice/ 
Potentially could point the Android to use an invalid DNS (as per above link).

To edit the hosts file, need to root the Android & use one of those editor (found
 one called X-plore) to edit the hosts file but doing so will void the warranty
(unless I have a way to unroot it back 'safely' without being detected)