Let me tell the story from the beginning: I installed Big Sur on an unsupported Mac using guidelines at Medium. In the guide it was stated that I should create a separate partition for Big Sur, and shouldn't install it on my current one. I had my SSD Called "Macintosh SSD" and later I created a partition named "Macintosh SSD Big Sur" of size 40GBs. After installation I wanted to clear the "Macintosh SSD" of size 80GBs(with old MacOS) and merge it with the new "Macintosh SSD Big Sur".
So, I used the command sudo diskutil apfs deleteContainer disk3 after which I had (free space) in /dev/disk1
I want to extend that 39.6GB partition which free space of 80,1GB but all the commands I googled do not work:(( Could you please guide me on what I should do now? Thank you in advance!