What are some really good extra curriculars I can start from scratch and have them be impressive in a month

Depends what types of engineering your interested in, but you could get involved in a club/start a club that has to do with biomedical engineering, chemical engineering, mechanical engineering, etc. and focus on things like that. If you're into the building aspect of engineering certain products you could try and invent something, or make a club like a "Shark Tank" club where people come together and create new inventions. You could host a competition and maybe make something that would benefit your school/community, and see if they'll impliment your design. You can also just do a general engineering club where you cover the different sub categories of engineering. Theres a lot you can do, but the more time and effort you put into it the better the EC will be.

You can start an engineering-related club or start a fundraiser and donate money to a tech company/to host a fair where little kids in your community can experience tech/etc. I feel like the second idea is more short term as you can start advocating for your fundraiser and close it within one month. The fundraiser itself would qualify as an EC and depending on how good your advertising is which leads to how much money you can get, it can become a really good EC. For the club idea, I think it's a bit too long term - you have to recruit people, make it an official school club, meet every week, decide what projects to work on, etc. Also, I'm sure there are quite a lot of coding/engineering clubs at your school already, so it's hard to get a lot of people to join and to actually accomplish much in a month.

TLDR: You can either form an engineering-related club or start a fundraiser. If you have extra time after the fundraiser and lots of money, host a fair/small stand for your community so kids can experience engineering/tech. Fundraising idea = more short term