If you want to look stylish and put together and trendy, then there is a certain kind of cardigan and a certain way of wearing cardigans that is very 2026.
If you don't care, just wear the cardigan.
It's so often about HOW you wear it and what kind of shape, colour, pattern etc the cardigan. Not ALL cardigans!
I had a mate who'd wear a gorgeous stylish dress for a wedding and would spoil the whole look with a boring basic black cardigan because she thought her arms were big. That's not the way. If she'd worn a feminine flowery day dress and a pink/lemon cute cashmere cardi it would've worked beautifully. The black with the dress was harsh and it just screamed that she felt insecure.
You can of course wear whatever the hell you want but it sounds like you want to look good.
Shorter soft wool round neck cardigans in a dark plum/burgundy or soft blur or lime/chartreuse/wasabi or persimmon (deep reddish orange) are very spring 2026, layered with striped shirt, silk neck scarf, colour clocked, softening up an adidas trouser, etc etc.
I bought a gorgeous cardi recently from neverfullydressed via vinted.