Yes of course, we can block someone on Gmail by simply creating a filter to the gmail. Follow these steps:
Open Gmail and go to the search column.
Enter the email of the specific person.
Then block that person you want to block without them knowing.
After that, Click on the “dropdown arrow” on the right side of the search column.
Choose the "Create filter" option.
Click the "Delete it" button to erase emails from the blocked person.
Then Click to save your all changes.
Source:
https://webmailup.com/how-to-block-someone-on-gmail/
