Mac OS Recovery: Disk Utility always partitions SSD
If you format your main internal disk from Recovery, Disk Utility will actually set the drive up ready to accept a new macOS. This will entail actually making 4 partitions, 3 of which will be nominally hidden from you.
If you don't need or want to see any of this 'under the hood' detail, you can set Disk Utility to only show Volumes, not all devices.
Cmd ⌘ 1 or View Menu > Show Only Volumes will do this for you.
if you really want to see everything that macOS hides from you, launch Terminal & type diskutil list
[this will not change anything, merely allow you to see it] - you'll see 'real' disks & volumes, & also synthesised ones which are virtual but necessary for the smooth operation of the system.
for example -
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_APFS Container disk1 1000.0 GB disk0s2
/dev/disk1 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +1000.0 GB disk1
Physical Store disk0s2
1: APFS Volume Macintosh HD 585.5 GB disk1s1
2: APFS Volume Preboot 21.2 MB disk1s2
3: APFS Volume Recovery 509.3 MB disk1s3
4: APFS Volume VM 20.5 KB disk1s4
Despite all this, all you will see in Disk Utility is either just Macintosh HD, or your drive's physical name [APPLE SSD SM056L Media] with [potentially an APFS container if your OS is new enough] & Macintosh HD inside that.