There is no conclusive answer to your question. IP addresses will still be leading, when it comes to reputation - which has been the historical behaviour with mailbox providers. More recently, domains have been taken more into consideration, especially with Gmail. However no major mailbox providers are sharing details on how the exact sender reputation is calculated.
With the adoption of IPv6, there are now exponentially more IP addresses available. This growth makes IP address reputation much more difficult for the mailbox providers to effectively monitor. To help deal with this added volume, mailbox providers are leaning towards more domain-based authentication for their filtering decisions, as this is a more manageable way for them to monitor a sender’s reputation.
Looking at authenticated domains to track and determine a sender’s reputation also allows mailbox providers to more easily see email traffic across multiple IP addresses and identify legitimate versus spoofed emails. This allows mailbox providers to get a more accurate reputation picture of a sender.
If you want to be entirely sure to have and fully separated reputation, separating both domains and IP address is the way forward. Do observe, that some mailbox providers also look across multiple subdomains to calculate your reputation, e.g. marketing.example.com, offers.example.com, and in some cases example.com will influence each other.
As in your example, you will be using different sender email address, but on same domain - hence an IP warmup is not needed at all.