It also helps to sit on a good chair, which isn’t necessarily the most comfortable. I currently sit on a used front seat from some ~1995 Subaru, and it used to be horribly uncomfortable but it forced me so hard to face forward and upright that I eventually got used to, which likely is not too far from a correct posture. That implies how wrong I am to be on this prestigious forum - but it helped my posture far more than a comfortable chair that faithfully held my body at a “sack of potato” posture.
I went from an office chair with arms I would lean on, to a regular folding steel chair with a cushion on it. It has forced me to hold myself upright and has thus fixed some occasional pains I was having from bad posture.
Yes, a facny chair can give you the false comfort of sitting in a poor posture and making bad habits. I prefer simple non swivel chairs for better posture and better grounding.
