@neilkumaran not sure about your hardware store but mine definitely would not have those. They are small metric screws. You would have a better chance asking a camera repair person or I would check with somebody that repairs cellphones for a living and see if they can spare those screws.
If nothing else, you can look into purchasing a complete screw set. Something [https://www.dhgate.com/product/full-set-screws-for-oneplus5-a5000-oneplus/470295755.html|like this] This is not an endorsement, just an example of what to look for. Going by the markings that I found, those screws are all metric from M2.0 M2.5 and M3.0 but no idea about the length. To find out what screw to use where, you would need to look through the guides [[Topic:OnePlus 5T]] as well as plenty of YT videos. Not difficult just time consuming