If the DNS lookups are done by the proxy or by the client itself depend on the kind of proxy configured and less if the proxy is configured in the browser or global to the system. When using a HTTP proxy (which works for HTTPS requests too) the DNS lookup is done by the proxy. If this is a SOCKS4 proxy it needs to be done by the client. With SOCKS4a and SOCKS5 it depends on the actual client and maybe additional configuration.
Anyway, even if the DNS lookup is done by the proxy the ISP can still see which domain name gets accessed, no matter if you access HTTPS sites or not. In none of the proxy protocols the traffic between client and proxy gets encrypted by default. This means the target domain can be extracted from the SNI extension of the TLS handshake. Note that some proxies might be able to use a HTTP proxy over HTTPS. But this is not the case for most browsers and needs special add-ons or advanced configuration access for other browsers (like in Firefox).
Thus, to hide which domain you access you should use a VPN and not a proxy or make sure that you access the proxy itself by HTTPS and not only the site you visit.