Will i lose anything off my device after my 21 days of extra storage expires?

within the past 2 days, I received my new IPhone, but before I finally got the number transferred over to the new one, on the old one I attempted to transfer the data from the old one to the new one without using iCloud and the 21 days of unlimited storage to transfer everything over, however I had to reset my new iPhone because the number wouldn’t transfer, so I reset but kept the esim and the number finally transferred to the new phone after that reset, but the option to transfer my data from iPhone to iPhone without iCloud wouldn’t work and it had me backup the old one to iCloud.

I don’t want to go through iCloud, since I have a rather substantial amount of storage primarily from the photos app, it will take a very long time to back up, I’d much rather just not deal with any of it with iCloud, but I’m concerned that I will lose all my data of primarily things from the photos app once the 21 days is over, if i cancel and delete the backup of the old phone from iCloud, after 21 days, will I lose everything from the old iPhone that was included in the backup?

essentially I just want to cancel and delete the iCloud backup on the old iPhone and be able to keep everything on the old iPhone without worrying about losing it once the 21 days is over

sorry for any confusion in this thread post, but I appreciate advice, just want to make the smartest decision I can based upon what the options are