My son did this at a similar age, as did my nephews. I honesty think it's just a developmental thing- the realisation that they can assert themselves a bit, and don't have to immediately fall into line with routine!
We stuck to our guns, which meant a few stressful evenings of going in and out, replacing dummies, shushing and patting etc.
We kind of wanted to maintain the message that bedtime was bedtime, but did so gently, with lots of reassurance and firm but fair responses. It did pass 😃.
That describes my situation exactly, mine is the same age as yours. He has no intention of going to sleep despite displaying his tiredness signs and having gone through is usual evening routine. We've just been bringing him downstairs and he happily settles on one of us. He'll eventually drop off and then stirs when he's taken up to his cot but settles well once in it. This approach suits us and him.... plus it's kinda nice having the cuddles as during the day he doesn't stop. We did try one night of laying back down, shushing repeatedly etc but it was really distressing and upsetting for all of us. Then we felt guilty he'd had a rubbish evening and not gone to sleep happy like he usually does.