The biggest likelihood is the phone you have is not used in the region it is intended. The servers that deliver the software 'over-the-air' are then unable to support the phone and updates are not sent.
The easiest way to identify is to check your software in the service provider information under settings - about phone - software information.
The three letter codes will tell where the phone originated and the software region it is.
If you post this info on here... it is searchable on the Internet which region and this might help to understand..... below is an example. My phone is OXM / EUX which is an unlocked phone from European regions and multi CSC.
https://technastic.com/samsung-csc-codes-list/Smiley
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User: Smiley
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My life is full of positives and negatives. I’m an electrical engineer.
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