No 'Shift' lens for these !!

Oh Dear -- converging verticals here but I'm not a 'PhotoShop' expert to straighten them !! 1986 LEICA M6 with outdated film in a cruise.
Interior, Navigator of the Seas, Royal Caribbean Ship -- 35mm f1.4 Summilux, 2006 dated Fuji NPS 160 rated 80 ASA

Cruise 02 by pentaxpete, on Flickr
Interior, Messina Church, Sicily Italy 35mm f1.4 Summilux at f1.4 and a flash, 2006 dated Fuji NPS 160 rated 80 ASA ,prints scanned

Cruise 04 by pentaxpete, on Flickr

Under the enlarger, you can make modest corrections by tilting the easel, and of course you can rotate the easel to straighten the "horizon." For a slight correction, this is often a good trick. Some enlargers also have tilting lens and film stages for even more flexibility in this regard, but ultimately, since the three-dimensional scene has already been converted into a two-dimensional image on film, the most you can do is to square one plane at one distance from the original camera lens, like using rear tilt/swing on a view camera. To correct all planes, you need rise/fall on the camera or a better place to stand.

That's right - also not easy snatching photos in the Church when in a Group with a Tour Guide speaking and about to move off elsewhere !

All you need is a rectifying enlarger. ;<)