Open the Messages app
Open the conversation from the sender you want to block
Tap the three-dot menu
Tap Block or Block number
Confirm the block
Open the Phone app
Tap Recents
Find the number you want to block
Tap the number or info icon
Tap Block or Block/report spam
Confirm the block
Open the Messages app
Tap the three-dot menu
Tap Spam and blocked
Tap Blocked numbers
Tap Add a number
Enter the number and save
Open Settings
Tap Privacy or Security
Tap Blocked numbers or Blocked contacts
Add the number manually
Open the contact in Contacts
Tap the three-dot menu
Tap Block contact
Confirm the block
Open Google Messages
Tap your profile icon or three-dot menu
Tap Spam and blocked
Tap Blocked numbers
Add the number if needed