There isn't much you can from blocking junk, spam or what every you want to call it. I've been try with out success for years and now with AI I have feeling it's not going to improve.
On a iPad about all you can do is block them. They won't delete until to do it.
To block them you have to press on the email and in the sheet that appears, press "Block Contact". I would also suggest that you go to Apps >Mail > Privacy Protection and enable "Hide IP Address" & "Block All Remote Content" if they are not already.
I wish that the bigger companies that are doing AI would take action on the spam problem with AI but I am not holding my breath.