How do eth based altcoins affect eth?

I have been trying to find how the relAtion of eth based alt oins affects eth as a whole. I am either bad at finding the searchable keywords or folks just don't want to talk about it.

When altcoins are based on ETH does this mean it will use ETH when transactions take place? IE it burns eth and such?

I am just researching some fundamentals such as if eth based altcoins get adopted/popular if this will make eth popularity(and presumably price) rise as well. I kind of feel like eths long term value is based of utility(vs simple store of value) so determing the scope of of utility is important.

Totally down for suggested reading if it is out there.

Thanks!