As iOS 13 is about to be announced in a few hours, I would suggest a brief delay before registering your complaints, otherwise you'll have to start over again
On a more serious note: keep in mind that a phone or tablet running iOS was never meant to be used in lieu of a desktop PC/Mac(book). That is one of the reasons that Apple will default to IMAP when setting up e-mail accounts, so that your tablet will mirror whatever you do with your main computer with regard to your e-mails. And batch deleting, or moving, e-mails is still easier done on a PC or Mac(book). I realise that there are more people every day who use tablets as a replacement for a larger computer, but this is one of the drawbacks. Whether Apple will address this issue in future iOS updates? Don't count on it, they'll want to continue selling Macs.
You could look into different e-mail apps with additional functionality, I'm sure they're out there but I haven't checked. The risks are that it may be something that you'll have to pay for, may not have the seamless integration with the other apps on your tablet, or may cease to function at some point due to discontinued development for some reason. Whereas the defailt Mail app will always work.... and if it ain't broke....