Larger Lock-Screen PIN buttons?
There are Apps in the Play Store that provide an alternative lockscreen. Have a look at this page to see some. But from a perspective of security, I would personally avoid using an alternative lockscreen app, as you give your whole security and privacy into the hands of one app. But that's a decision you should make on your own. Android itself does provide the functionality to let other apps handle such important things using Device Administrator rights.
Other workarounds would include using an alternative locking method like Smart Lock or installing another ROM, for example LineageOS.
I personally would try getting used to it.