Thank you very much for your answer.
These were also the solutions I had come up with.
The 404 one is really what I was searching for.
I was hoping to find another alternative.
On another site someone told an idea that won’t take long to do.
I share it here, if it can help anyone other than me:
I exported the dates and permalinks of my posts with WP All Export. I modified the .csv to keep what I wanted and add a redirect column I wanted.And I imported the file with a redirection plugin.
Thank you for your interest.
I will delete every post of 2020 and 2019. I would like their links to be redirected to https://website.com/blog to avoid 404 pages. I would like to keep my actual permalink (https://website.com/%postname%/)
