Stripping baby clothes

If someone has directions ill screenshot them and do it. Ive seen many different ways on google and just want to ask moms who knows what works. Do you wash with dreft or all free and clear afterwards? What do you do? Put it in bathtub or sink or does it matter?

I dont mean just to wash, this is for hand-me-downs only. I saw there is a technique where you somehow strip the clothes in a bathtub or sink and let it sit over night. The water gets real yucky and brown from any bacteria or dirt from the clothes. I wouldnt do this with any new stuff i have.