Macro can be a really technical subject. The main concepts you want to understand are magnification and working distance.
The current macros that Pentax offers all do 1:1 magnification. They can all take a shot of something that's the size of the sensor, 16mm x 25mm, and have it fill the frame. In food terms, that's not a lot of food. The lenses you mention can do 1:4 or 1:5 magnification. For a plate of food, that's good enough. For one cookie, it's not enough.
Working distance is how far your lens can be from the subject to get that magnification. This is where the lens's focal length comes in. The DA 35mm f2.8 macro is really close to its subject at 1:1 magnification. The DA 100mm f2.8 WR is farther away. The image would be the same size with both lenses. Smaller working distances can mean disturbing the subject or creating shadows.
I think you don't really need the 1:1 magnification; 1:2 is fine and 1:3 is probably OK. The DA 18-55 does 1:3 and it's cheap. A few other zoom lenses will do from 1:2 to 1:3. The images won't be as sharp as a dedicated macro prime. An accessory like the Raynox may be enough. I'm not familiar enough with them to know. Used dedicated macro lenses shouldn't be too costly. The Pentax-M 50mm f4 Macro is 1:2, should do the job, but is manual focus and manual aperture. That means a little less flexibility and some challenges with flash. There's a lens made by Cosina that's 100mm f3.5, 1:2 macro with an accessory filter to go to 1:1. It was sold as a Pentax, Cosina, Vivitar or Phoenix. Some versions are autofocus, some manual focus.
I have this lens, a 90mm f2.5 1:2 macro, which should be excellent. It's autofocus. I'm not the seller:
https://www.pentaxforums.com/forums/24-photographic-equipment-sale/279016-sal...-f-2-5-af.html