Merge "free space" with Mac OS Volume 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 &quot;Macintosh SSD&quot; and later I created a partition named &quot;Macintosh SSD Big Sur&quot; of size 40GBs. After installation I wanted to clear the &quot;Macintosh SSD&quot; of size 80GBs(with old MacOS) and merge it with the new &quot;Macintosh SSD Big Sur&quot;.
This is what I initially had after formatting partition with the old MacOS

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!
Your free space is before your disk2. The start position of a partition is fixed, and you can only resize the partition by changing the end position. You should back up your data, erase the disk as one partition and restore from backup.