after two hours she’s still up and down the cot, standing up and sitting down, pulling the blankets up and showing no signs of settling
When baby learns to pull to standing, this is quite a usual phase to go through with sleep. Its solvable, don't worry.
Firstly, a baby sleeping bag is much easier for a mobile baby to sleep in, rather than blankets. It keeps baby covered and at an even body temperature even with lots of wriggling and movement.
Secondly, develop some independence of movement. This is important generally, but in particular at bedtime.
So stop doing things that baby can physically do for herself. Every time you put her in the cot, out her in standing up. Tsp the mattress and ask her to lie down. Get her to lie down herself, stop physically lying her down.
Luckily young toddlers are really keen to show you how clever they are, so almost universally they like following instructions. Follow this through in the daytime too - give instructions like take this to Daddy, come here (to get her to climb on the sofa, or come to where you are) rather than picking her up or going to her. Also games like Where's Your... nose/fingers/feet etc.
Its all about developing independence. With that independence comes the ability to choose to do as she's asked, and (as will become the battle) to choose not to do as asked. So the need for firm boundaries and high behaviour expectations - which is what this sleep regression is all about.
Once she (a) physically can go from standing to lying down on her own, and (b) Can understand the instruction to "lie down", then it comes down to being a broken record.
Being calm, not losing you cool, but very consistent is what will help her learn.
So put her in the cot, already in a sleeping bag, stood up. Tap the mattress and tell her to lie down. Dont lie her down. Similarly if she has a dummy or comforter, put these in the cot and get her to find and pick them up herself, don't hand them to her.
Then stay close, you need to watch her like a hawk so that you can respond instantly.
If she goes for standing up, respond before she's even sat up. Tap the mattress and tell her to lie down. You are teaching her that at sleep time, you expect her to lie down and stay lying down and that nothing else is acceptable behaviour.
Having the sleeping bag helps here, less faff than blankets. If she manages to stand up, tell her to lie down again (they are very eager to please at this age). If not, pick her up and calm her with a cuddle. When calm, start again - into cot standing up, tap mattress and tell her to lie down.
Just be mega repetitive about it, over and over again to establish the expectation she lies down... by choice... so she independently deciding yo do as you ask.
Once she (eventually) lies down, you putting your hand on her chest may calm and sooth her. But mostly just wait. Keep insisting she lies down, hand on chest yo sooth. If getting distressed lift and cuddle to calm (not to sleep, to calm only) and start again from the beginning - putting into cot stood up.