I hope these few articles will help you.

https://medium.com/@jimmysong/understanding-segwit-block-size-fd901b87c9d4
https://www.coindesk.com/bip-148-segwit2x-bitcoin-scaling-compromise-might-not-easy/
https://99bitcoins.com/bitcoin-fork-segwit-vs-bitcoin-unlimited-explained-simply/
https://medium.com/@jimmysong/segwit2x-what-you-need-to-know-about-the-2mb-hard-fork-27749e1544ce