Many times we wish to share our Wi-Fi connection to other gadgets or probably to a friend. You might say "why don't you just connect to the same Wi-Fi or why don't your Friend Connect to that Wi-Fi ? "

Let's look at it this way. You're connected to a Wi-Fi with access granted to only registered users (like those in colleges or our work places). Registered users only have one session. By one session I mean,  users can only be logged into that Wi-Fi network through a single mode of connection (on only one device at a time).

This implies that you have to log out connection on one device to connect the other device. This implies that your friend will have to watch you surf the internet alone. That's totally not cool!!!  What if you can connect a single Android phone via Wi-Fi and spread out the connection via the the Android's hotspot? Thus, putting smiles on people's faces and be happy.

YES, you can DO it !!!

Mobile device can not act as a wifi repeater so that it can be a wifi hotspot device, but by doing some geeks with a awesome Android App, it can be quite easily done.

It is not required to root your device. WHAT YOU HAVE TO DO IS; 

Download and Install an App “Netshare” from Google Play store
After installation,  open it, it will generate a Network ID and password, use this to connect to other devices

https://icmaxblog.com/posts/turn-on-wifi-hotspot-while-connected-to-a-wifi/