The Block feature on my phone is definitely one of my favorites, Maymac. From the iPhone 8, you can select the number in your Call Log or text thread> select Edit > Block Caller.
You can also tap Settings > Phone > tap Call Blocking & Identification > tap Block Contact, then enter preferred contact(s) by typing in search box or scrolling through list. To unblock, tap Edit (upper-right), then tap red minus icon and tap Unblock to confirm.
Please let me know if this helps.