Hi everyone, I'm new to adenium plants, just wondering if these two look a little dehydrated? The trunk is a little spongy and maybe a little sunken? They are in 7cm pots and approx 5" high.

They look just the opposite - very hydrated

Your 3rd picture - the plant on the right looks okay ....but the plant on the left looks like it may be suffering

Are you entering winter ??

If so, need to cut back drastically on watering and allow your plant to enter dormancy ...

Choose a watering schedule you are comfortable with:
1) once every 3 months (90 days)
2) once every 60 to 75 days

Might do a little checking and see if everything is okay below the soil line ...

pull the plants out of the pots, knock off any existing potting mix - while the roots are exposed ...look over the roots for any root damage, discoloration - or abnormal appearance ...and if anything looks mushy or like a slime .....

if roots are white and firm, then you are probably alright ... but if roots are mushy, off white then you have root rot

After the root check - re-pot with a more chunky, rock, grit, sand potting mix

I agree. That soil mixture looks deadly.

Ok so I've taken both plants plant from their pots, No sign of any rot at all on either plant. Both lots of roots are as dry as chips... and yes, we are entering winter.

Roots look okay .... Leaves look okay .....so far so good

Here is a potting mix that I have used for years ..... some of it may, or may not be easy to find ...

Mix together:

2 Part: Coconut Coir -
1 Part: Poultry Grit (chicken grit) /or Pea Gravel
1 Part: Sand - coarse Builder's Sand, or Leveling Sand, or Horticultural Sand (sift out fine silt)
1 Part:: Lump Charcoal - Break-up (crush larger pieces) (sift out fine silt)
1 Part: Lava-rock – (volcanic cinders or pumice) (crush larger pieces) (sift out fine silt)

Optional: mix with above

1 Part: Redwood Bark / Orchid (Phalaenopsis) Mix - Break-up, cut or crush larger stems & bark
1 Part: Perlite - coarse

Unable to find Coconut Coir ?? - substitute with regular Soil Mix

If unable to locate the ingredients above:
Use a half and half mixture of Orchid / Phalaenopsis Soil Mix (mostly bark and rocks)
mixed with Cactus / Palm Mix

Since you are entering winter ... water plants with a good soaking ... then wait 2-3 weeks to water again ....ensure water flows out of the bottom of the pot almost as fast as it was put on top of pot

After that 2nd watering .... Choose a watering schedule you are comfortable with:
1) once every 3 months (90 days)
2) once every 60 to 75 days

Awesome thank you so much. 🤞🏼🤞🏼🤞🏼