Came here to say what PPs have said. "Your goal as the parent of an autistic child is to help them thrive. It is NOT to help them appear neurotypical." Is spot on
I have a DD who we think is autistic but her communication/speech when assessed was 2 years above her chronological age (3yrs vs 5yrs) but we STILL have screaming when trying to get a coat on and get out the house. Mostly now it's sensory but pressure of the transition doesn't help, when she was younger transitions were a bigger issue. I try and give plenty of warning about when we need to leave and what she needs to do and then give her space to sort it out. I try and keep words and even eye contact and my presence to a minimum because it's a trigger for her so I sort myself and DS out in the meantime now but obviously when younger she needed more help.
Maybe you could teach the coat flip so they can have more autonomy?
Maybe a this, then this, then that type chart to explain going out? Coat and shoes, then bus, then playground type thing
Maybe a different option of warm clothing? Gilets are less sensory input for DD and weirdly a light weight snow suit is working relay well for her and her previously good/comfy coat is AWFUL. She's 4 and started wearing underwear before 1.5 years but at 3 they became absolutely intolerable, leggings/trousers/tights then went too and she'd worn them since birth. None of us is her choosing not wear that stuff, she just can't manage it.
You mentioned toddler groups, have a look around and see if there's anySEN ones near you, childrens centers would probably be helpful here. Portage is a service that works with SEN kids and ours has a playgroup but I've been told DD would be the only one who can talk so we've not taken her, she likes to play with older kids so wouldn't be a great environment for her. Meeting parents in a similar position is nice too.
@gogohmm ABA therapy is considered abusive by many autistic adults now and it's not recommended by them at all