How to keep latest copy of previous Time machine?

[resting]

How does Time machine work?

I have a Time machine backup of my old system before I formatted and reinstalled the OS and everything.
I want to keep a copy of the latest backup from previous backups and set up a new Time machine for the current setup.

This is what's in the previous Time machine backup
2019-01-01-185033
2019-02-10-032636
2019-03-01-231022
2019-04-04-070026
2019-04-04-073854
2019-04-04-081339

Is 2019-04-04-081339 the latest copy that contains everything?
Or does it only contain the differences between 2019-04-04-081339 and the previous backup?

Reason being I want to remove the old backups to free some space for Time machine on my current setup.

 

[KALLT]

Each snapshot is a complete backup. Time Machine merely uses some tricks under the bonnet to save space, such as by referencing the same file across backups if it hasn’t changed in between. Deleting a snapshot will only result in a deletion of those files that aren’t used by any other backups.

You can delete snapshots with the Time Machine app or the tmutil command-line program. You should never ever use Finder or like to delete the folders.