Small cauldron

Asides from the one mentioned by gibi, here are other substitutes:

This one works as a grill: sims4.aroundthesims3.com/objects/history_challenge_cc_03_bronzeage.shtml

This one works as a bonfire: simsworkshop.net/resources/cauldron-of-fire.1575/

This one is decor but it produces steam: maxismatchccworld.tumblr.com/post/187634908055/ksjdfnsjdfn-sdjfhbsjdf-sdjfsjdf

This one is a fireplace: www.thesimsresource.com/downloads/details/category/sims4-objects-buildmode-fireplaces/title/goul-halloween-2020-cauldron-fireplace/id/1510859/

These ones are standalone cauldrons that are portable in your sim's inventory: maxismatchccworld.tumblr.com/post/640380012831326208/portable-cauldrons-hi-everyone-long-time-no-see?is_related_post=1

This mod allows you to brew herbalism remedies using the cauldron: www.patreon.com/posts/brew-herbalism-41650000

There was a functional small cauldron in neil simming's witches and warlocks modpack but it sadly hasn't been updated.

Hopefully, some of these might help.