Updating shifters on mountain bike
It's fine to say something like 'you may not see much benefit with one or two extra rear ratios'. Maybe they would get something out of the experience of doing the upgrade work themselves and the changes to the bike are secondary.
Since it's a newer bike, it could have 130 or 135mm spacing and just have a 6-speed freewheel on it. However its a slippery slope of knock-on upgrades that can cost more than a nice, lightly-used bike. All i'm asking is there a set,or equivalent where i can replace - at least the shifters to a more modern ones,and front derailleur without having to break the bank. I really don't want to spend a lot of money on an upgrade, but an up grade of some sort is necessary because of simple wear and tear.(Well I did some research, turns out that the upgrades alone will cost you a considerable fraction of the cost of your bike, especially since the country you're living in doesn't have an abundance of upgrade parts.) Also, you might need to get a new chain along with all the other things but it won't be required if you're lucky and you get a similarly spaced cassette.--- As can be seen, the upgrade costs make about 47% of the bike's market price, which makes the upgrades highly absurd, also considering that with this money, the person can probably sell this bike and upgrade to a bike of a nicer build and his desired gear set-up. Down vote was for lecturing the OP that they ' DO NOT' need the upgrade in the first half of the answer.First try backing out the limit screws, but if you still can't get the chain to reach the biggest and smallest cogs then you're up for a new rear mech.
SUMMARY I have upgraded two bikes - one was a 20" folder, which changed from a 1x6 freewheel to a 3x8 freehub.
I ride a Hero Sprint, MTB, with 6 gears in rear and 3 in the front.
I am thinking about upgrading my 6 gears to something like 7 or 8.
Once you have a wider hub, you can fit a wider cassette (don't bother buying a hub that takes a freewheel - that way lies bent axles and wallet-tears) So you need a cassette, which will require a new chain.
Generally speaking 6/7/8 speed chains all use close to the same width, but you want an unworn chain to help prolong the life of your cassette. They wear slower than the cassette, but if the chain is making bad contact it could be time for new chainrings.
The OP would do well to consider selling the bike and purchasing a new or used one with better features.