Finding a dead link on a relevant page and offering your own resource as the replacement solves a real problem, which is exactly what earns a yes.
Find Relevant, Authoritative Pages
Resource and links pages in your niche are the best hunting ground, since they're built specifically to link out to useful content.
Confirm the Link Is Actually Broken
Double-check before reaching out; a working link mistaken for broken undermines your credibility with the outreach.
Make the Replacement Genuinely Useful
Your resource needs to actually match or improve on what the dead link used to point to, not just exist as a placeholder.
Next step: Use the Broken Links Finder to scan relevant pages in your niche for dead outbound links worth replacing.