This is a behaviour issue, not a sleep issue directly.
And at 11 months old, this may well be the first time you've come across a behaviour issue, whereby you have a set of expectations and DC is refusing to do what is expected. Welcome to your first glimpse of the Toddler Years!
Some babies do not inherently understand that in order to go to sleep, they must be still. So this is something you need to actively teach. It's a case of "Mum Knows Better", so although baby may want to stand up, sit up, roll around, that you understand more than your baby does and you know baby needs to lie down, be still and be quiet in order to go to sleep.
So set these expectations. When in the cot, baby must lie down (by himself), must stay lying down, must stay still and must not be fussing around. That sounds daunting, but it's not. You can have these expectations of your 11 month old,
So start off with - always put baby into the cot standing, tap the mattress and say "lie down". Practice this in the day, so he can understand and follow basic instructions like this.
Likewise the pacifier or blankie, put them in the cot mattress and tell baby to "get dummy" (or whatever word you use). Develop that independence that this boundary pushing is evidence of. Dont ever hand pacifier or blankie to baby. If it is thrown, put it back into the cot for baby to get himself.
Your presence is needed in the room at bedtime because you need to constantly, relentlessly, reaffirm the boundaries of expectations. Develop a simple mantra that sums up your expectations. For example "sleep time now, we lie still to sleep".
Every time goes for sitting up or standing up, tap mattress, repeat mantra and expect baby to lie down. If not, immediately lie baby down and place your hand firmly on the chest to reaffirm the expectation that baby is to lie down.
Any fussing or rolling around, firm hand on chest/shoulder to still him. If his arms are flaying around, hold both his hands in one of yours. If his legs are flapping, place a hand over his thighs or knees to still them.
Keep your hands on his to reaffirm stillness until he's calm and not fussing against it, only then lift hands off him and wait quietly by his bed for his next attempt to push boundaries.
Keep on reaffirming the expectations , without any wriggle room or negotiation - you want baby (a) lying down at all times in the cot - not sitting up or standing (b) Being still - not thrashing around (c) being quiet - sucking on the dummy not shouting
So all the time, consistently, keep up with these expectations. Expect him to lie back down, or lie him back down yourself. Expect him to be still, or keep him still yourself (gently, but firmly). Expect him to suck for soothing on the dummy instead of crying, so keep the active sucking going.
What you need to understand is that (now you have a baby with the growing independence like a toddler) is that while you cannot physically make him go to sleep, you can make him follow your rules without negotiation when, as a parent, you know it is in his best interests. So you can make the rule and expect him to follow them that at bedtime he will lie down, lie still and lie quietly. Then you can all wait and because you know best, you know that he'll go to sleep because he needs to sleep. But you need to stop giving him permission to actively fight against going to sleep when he needs to go to sleep. He needs to understand that this type of behaviour isn't acceptable.
There will be many, many times when you come across behaviour that your child does that is not acceptable. Sometimes, like sleep, this unacceptable behaviour will be such that his safety or health is in jeopardy if he doesnt follow your instructions, even if he doesnt want to follow your instructions. So learning that you will be consistent in these situations will help you a lot when facing the Terrible Twos (and Threes)