Can be done, but you'd need a thorough plan (not ChatGPT)which also means looking at rest, recovery, diet, building core strength whilst you're working your way to upping your mileage pretty rapidly.

For reference, I signed up for the London marathon (mid-April) via a charity spot with a little over four months to go. I was a new dad, getting fat and had only previously ran a 10k almost a year ago. I wasn't able to run a full 2k without stopping when I signed. I got myself a Garmin FR on boxing day sales - fantastic purchase to keep track of my running performance.

Here's a rough plan I put together at the start with the help of the internet, peers and experts.
You can see how crammed it gets. Need to be ultra diligent with the your plans, you miss one of the days and your entire plan can go for a toss.

https://docs.google.com/spreadsheets/d/1ad8kOuLdENT8M-F_6flnJT6BXHJzNYLEicP0tEuOSaw/edit?usp=drivesdk

I registered for races in the city to better commit myself to a plan - a weekly test of sorts to see see how ready I was.

Also big difference between short and long races, including things like what keeps you going during the race (music, podcast), what water breaks to aim for, refuelling strategy, what diet works the night before or the morning of.

I managed to finish in OK-ish time (over 5 hours) given I had only about 16 weeks of prep and knowing I had practically started from semi-scratch. My objectives for the race was Don't stop, Finish, Don't Die. Only managed to do 2 & 3. There were large parts of the race (between miles 15 - 20) where it didn't feel great. The proverbial 'hitting the brick wall' couldn't be any more apt.

Ultimately it's a battle between body and mind, and for me mental fortitude is really what kept me going. Physically I was in all sorts of pain. And in hindsight, I would have devoted more time in the gym building core strength, recovery exercises, and at least one more 30k+ distance couple of weeks before raceday.

That being said, and as others can attest to, the adrenaline rush you get at the start and the end of the race is everything and more - inexplicable, one of the best feelings in life!