Hmmm... well he is 2.5 years old.
With each age-stage, there are different cognitive developments.
So, what is expected... may not be what the child can do all the time perfectly each time. Kids this age, do not have perfectly attuned or developed deductive or inductive reasoning. They don't think in terms of 10 steps ahead of their action. Nor do they have perfect hindsight. And at this age they do not have fully developed impulse-control nor fully developed emotions or communication.
Sure, at this age rules and boundaries and routines, are taught.
But kids also make mistakes. Childhood. And sometimes they don't even know they are making a mistake.
And mistakes versus on purpose disobedience or defiance, are two different things. So discern that.
Sometimes, time outs are not effective. Or the kid gets desensitized to it.
But yes, consistency is important.
A kid, goes through each day with being told "No" a lot. It must be frustrating.
But along with teaching them "no"... it is also important to talk with them about things. And per their age and what they can understand.
For example: what if your Husband ALWAYS told you "no" for mostly everything or had to correct you for everything you did or said? And he made you stay in your room for timeout. But he never explained the reason why, but that you always got told no or punished or told you were wrong, and all you know is that he doesn't like anything you do or say and nothing is ever good enough or that you NEVER met his expectations??? But then sometimes he gives you a hug or kiss. Would it feel authentic or would you feel proud? Would you feel good about that?
Would you like him for doing that?
Also important is to teach the child how to express themselves. Too.
Toddlers, have so many things in their heads and developing imaginations... but physically, they may not be able to actually DO what they are thinking. The Toddler age is awkward.
They may want to ride a bike... but may not be able to actually do it, nor perfectly. Then they get frustrated. And fussy. So they need to also be taught about how to communicate and the names for their feelings.
It is not instinct.
For my kids, discipline is for downright defiance. But if they are simply making a mistake or doing something for which they are not astute at yet... I don't punish them. I coach them on it. My expectations are also reflective of their age stage. I cannot expect my 5 year old and 9 year old to be on the same ability or comprehension level. Nor when they were 2 and 6 years old.
At this age, concurrently, Toddlers do go through the "no" stage and saying the opposite. So, it may be your Sitter, or it may very well be just your child's age-stage and development. So discern, that.
There are many ways to handle a child saying "no." It does not always have to be handled with hardness.
Another reason why Toddlers may tantrum is, they do not yet know how to communicate effectively, nor know the names for their feelings, nor even know what they are feeling. They are 2.
At this age, with both my kids, I taught them the names for feelings, and how to say it. It takes practice. And practice tones of voice, in a fun way.
Or Toddlers tantrum because they are over stimulated or tired or hungry.
Those are common triggers.
I also did not scold, if my kid was "grumpy." IF they cold articulate that to me, and tell me in a sharing way, I would redirect them. I didn't expect them to be smiley faces all the time. But we worked on "how" to express things, and so that they knew they could tell me of ANYTHING in their heart. And not be afraid that they would be punished for feelings. Some kids just need to learn how to say things... and the words for it.
So many things, that are taught and expected at this age.
Toddlerhood is not easy for child or parent.
Also, instead of always saying "no" to everything, use other words. At this age they are also learning "concepts." ie: "danger," "hot," "stop," "hurt," etc. Tell him why, instead of just no. But long drawn out explanations are not effective at this age. Keep it short and plain.
Expectations needs to be age appropriate.