Universal healthcare doesn’t “bring down capitalism” and doesn’t mean socialism. It’s just a norm of civilized capitalist world, one of the achievements of the working class that became entrenched in policies. Same for guaranteed income. All good policies, but can absolutely exist in a non-socialist world.
Socialism is characterized by common ownership of the means of production, i.e. all the big businesses go away and the control of industries is public, either through government or worker’s cooperatives.
Neither Democrats nor Republicans offer anything close.
(Socialist political groups can advocate for things such as universal healthcare/UBI/etc, but their endgoal has to be the eradication of private property)