Can I increase RAM from 8GB to 16GB on this model?
No, you can't! As stated in Apple MacBook Pro 13-Inch "Core i5" 2.3 Mid-2017 Specs:


  This notebook also packs 8 GB of onboard 2133 MHz LPDDR3 SDRAM (which could be upgraded to 16 GB at the time of purchase [for US$200], but cannot be upgraded later)


In a teardown of a similar notebook (a MacBook Pro 13" Touch Bar 2017) the RAM is visible outlined in green - it's apparently soldered:

Motherboard*:


    
    * Source:  iFixit.com. Photo credit: Sam Goldheart and licensed under CC BY-NC-SA 3.0.