You can cook veg into the liquid and then blend to make a lovely thick soup.
If you want chunks of veg, just take out half the veg, liquidise the rest, and return the chunks to it.
Some veg lend themselves to this more than others.
I find mushrooms thicken gravy beautifully, while adding fab flavour.
And tomato, onion, broccoli and cauliflower thicken soups.
Aubergine gives a beautifully silky smooth texture.
Peas give a good 'body'.
It is mainly a question of trial and error.
I used to regularly make soup as part of my job, back in college.
It honed my soup making skills, but the family were always complaining that I used up all their veg in soup.
Haha! It used to make me laugh, because there I was, going through their fridge, getting rid of all the tired old veg for them, to prevent waste - choosing the ones that were elderly and desperately needed finishing up. And they were whinging because I had deprived them of veg they were going to eat for days, apparently.