Are ETF values tied to the stocks they contain?

So, I understand how stocks go up and down, someone buys and someone sells, the value of the company has no impact other than what people are willing to pay to be part owners.

What I don’t understand is how ETFs get their value. Is it the same thing, just buying and selling at a certain price or do the values of the companies within them matter. If you had an ETF that was 25% Apple, Tesla, MSFT, and Google, and Apple went up, would the ETF price automatically go up? trying to reconcile how sale price works while also understanding how something like VOO can track perfectly with the S&P.