There are also some smaller, specialized fanfic archives that might have such stories. However, these can be a bit harder to find. You could try doing a general web search using specific keywords like 'Harry Saves Vernon fanfic archive' and see what comes up.
You can start by looking on popular fanfiction websites like FanFiction.net or Archive of Our Own (AO3). Just use the search function and type in 'Harry Saves Vernon' and you should get a list of relevant fanfics.
Some Harry Potter - focused fan communities on social media platforms might also be a good place to ask. For example, there are groups on Facebook or Reddit dedicated to Harry Potter fanfiction. Post a request asking if anyone knows of any 'Harry Saves Vernon' fanfics and you may get some useful links.
A practical answer is Chapter 88, because it turns the idea into a concrete scene. The chapter opens with She wanted to refuse, but didn't have the courage to do so., adds pressure through Jiang Yan immediately stepped forward, "I have one point, quick, quick,..., and ends on Let's go," Jiang Li.
If you want the clearest chapter reference, go to Chapter 76. Early on, Thinking of this, the aunt repeatedly praised, "Girl, hearing your words...; later, the chapter leans on I'll go back and tell this to my child; he will definitely be motivated to....
A practical answer is Chapter 74, because it turns the idea into a concrete scene. The chapter opens with Having seen Jiang Li's ID before, he knew that this person named Shiguang..., adds pressure through It's not just a banner we are talking about;
Chapter 81 is the strongest chapter-level answer because it starts from Qi Tianyu, who chose curry beef rice, received a piece of curry and a... and follows through on The summer on the Southwest Plateau is no joke; the sun at three o'clock....
Chapter 78 is the strongest chapter-level answer because it starts from He Yun, too, tidied up and walked over to rest in the shade of a tree. and follows through on [HAHAHA, is it just me or does Movie Emperor He seem to be showing off a....
The best chapter pointer here is Chapter 79, "Finally, I'm not the last one anymore!". It opens with Jiang Li leisurely said, "I bought this weeding machine, and according to... and closes on Um..." Wen Jiaojiao bit her lip, "Could you, could you lend me the weeding....
Look to Chapter 77 for the clearest answer. It begins with Wen Jiaojiao's reminder calmed Shu Yan down., keeps building through Indeed, the wild mushrooms on the Southwest Plateau were complex in..., and lands on But who knew that the next second, the lottery box would be handed over to....
Chapter 80 is the strongest chapter-level answer because it starts from Jiang Yan and Wen Jiaojiao, one so smug he was almost ascending to the... and follows through on arrogant princess with Princess Disease, I'm totally for it, fam.] [Hahaha....
A practical answer is Chapter 93, because it turns the idea into a concrete scene. The chapter opens with Jiang Li looked back and saw several aunties linking arms, walking up the..., adds pressure through Even if they were hiring actors, could they really come up with such an..., and ends on I.
If you want the clearest chapter reference, go to Chapter 73. Early on, Director Sun, tongue-tied, finally managed to squeeze out a sentence,...; later, the chapter leans on But isn't it due to your production team's lack of consideration?.