There is no definitive answer to this question as the value of a used iPhone XS Max will vary depending on a number of factors, such as its age, condition and whether it is locked to a particular network. However, we can take a look at some online selling platforms to get an idea of how much a used iPhone XS Max might sell for in Nigeria.
On popular classifieds site OLX, there are currently over 100 listings for used iPhone XS Max phones in Nigeria, with prices ranging from around NGN 90,000 (roughly $250 USD) to NGN 500,000 ($1,400 USD). The average price of these listings is just over NGN 200,000 ($560 USD), although it is worth noting that many of the cheaper listings are for older models or phones that are locked to specific networks.
Similarly, on Jumia - Nigeria's largest online marketplace - there are also hundreds of listings for used iPhone XS Max phones. Prices here start at around NGN 80,000 (roughly $225 USD) and go up to NGN 400,000 ($1120 USD), with an average price of just over NGN 200,000 ($560 USD). Again, many of the cheaper listings are for older models or phones that are locked to certain networks.
From looking at these online selling platforms, it seems that a used iPhone XS Max could sell for anywhere between roughly $250-$1400 USD in Nigeria, depending on factors such as age and condition.