The website mentioned give followers but these are robots ones means people that are not interested on what you are providing as content and follow your account for points and may unsubscribe later or even not interact in your posts means all websites where follow for points or money falsify results for nothing.There are several ways to increase your followers on instagram, I think the main thing you should do is look for a specific niche if that is what you are looking for, upload quality content related to that niche, dont use like4like strategies because this strategy no longer work because instagram has measures for this, you could use facebook ads to try to generate traffic to your instagram account, you can also try to do some kind of raffle if you have the resources, any raffle is fine, even if it has a lower economic value the thing you raffle.