Some credit card companies have card generators (Capital one has Eno, Amex has one I believe, Citi calls it Virtual Card Generator etc) but you can also use privacy.com, revolut and I think there's an app called token or something?

I think I pay for everything online with my privacy cards now. It's just easier to keep track of stuff when you get alerts after a company charges a closed card, or tries to charge you more than your card limit that you set up.