I sync up how Familiars, Animal Companions and Steeds work like so:

Spoiler: Summons
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Find Familiar
1st-level conjuration
Casting Time: 1 minute
Range: 30 feet
Components: V, S, M
Duration: Instantaneous

You summon a spirit that assumes the form of an animal. Choose a beast that is no larger than Tiny size and that has a challenge rating of 0. Appearing in an unoccupied space within range, the familiar has the statistics of the chosen form, though it is a celestial, fey, or fiend (your choice) instead of a beast.
Your familiar acts independently of you, but it always obeys your commands. It acts on your initiative, but it cannot take the attack action.
When within 100 feet you can communicate with your familiar telepathically, and when you cast a spell with a range of touch you can have your familiar use its reaction to deliver the spell using your attack modifier.
As an action, you can dismiss your familiar temporarily or permanently. Temporarily dismissed familiars disappear into a pocket dimension where it waits until you summon it again as an action.
A familiar that drops to 0 hit points disappears, leaving behind no physical form.
While you have your familiar, you cannot recover the spell slot used to summon it.
If you cast this spell while you already have a familiar, you instead restore your familiar to its hit point maximum and can cause it to adopt a new form that meets the same requirements above.
At Higher Levels: If you cast this spell using a spell slot of 3rd level or higher, your familiar can be of CR 1/2 or lower and can be a beast of up to Small size.

Find Companion
2nd-level Conjuration
Casting Time: 1 minute
Range: 30 feet
Components: V, S, M
Duration: Instantaneous

You summon a spirit that assumes the form of an animal. Choose a beast that is of large size or smaller and that has a challenge rating of 1/4 or lower. Appearing in an unoccupied space within range, the companion has the statistics of the chosen form.
Your companion acts independently of you on your initiative, but it always obeys your commands.
When within 100 feet you can communicate with your companion telepathically, and when you cast a spell with a range of self you can choose to touch your companion to also target them with that spell.
As an action, you can dismiss your companion permanently.
A companion that drops to 0 hit points disappears, leaving behind no physical form.
While you have your companion, you cannot recover the spell slot used to summon it.
If you cast this spell while you already have a companion, you instead restore your companion to its hit point maximum and can cause it to adopt a new form that meets the same requirements above.
At Higher Levels: If you cast this spell using a spell slot of 3rd level or higher, the companion is up to CR 1/2. If you use a spell slot of 4th level or higher, the companion is up to CR 1. If you use a spell slot of 5th level or higher, the companion is up to CR 2.

Find Steed
2nd-level Conjuration
Casting Time: 1 minute
Range: 30 feet
Components: V, S, M
Duration: Instantaneous

You summon a spirit that assumes the form of an animal. Choose a beast that is of large size (or medium if you are small) and that has a challenge rating of 1/2 or lower. Appearing in an unoccupied space within range, the mount has the statistics of the chosen form.
Your mount acts as a controlled mount, but it always obeys your commands. It acts on your initiative, but it cannot take the attack action.
When within 100 feet you can communicate with your mount telepathically, and while riding your mount if you cast a spell with a range of self you can also target your mount with that spell.
As an action, you can dismiss your mount permanently.
A mount that drops to 0 hit points disappears, leaving behind no physical form.
While you have your mount, you cannot recover the spell slot used to summon it.
If you cast this spell while you already have a mount, you instead restore your mount to its hit point maximum and can cause it to adopt a new form that meets the same requirements above.
At Higher Levels: If you cast this spell using a spell slot of 3rd level or higher, the steed is up to CR 1. If you use a spell slot of 4th level or higher, the steed is up to CR 2. If you use a spell slot of 5th level or higher, the steed is up to CR 3.

So they all follow pretty much the same framework.

Artificer Steel Defenders, Druid Wildfire Spirits and Pre-Tasha's Animate dead and Conjure X spells operate on the bonus action command ala Summon X spells from Tasha's. These creatures are either not smart enough to act on their own or are generally not disposed to in the first place, requiring you compel them to act. If they don't disappear when you lose concentration/fall unconscious they will use their action to dodge, disengage or dash as appropriate.
Artificer Homunculi are basically special Familiars the same way that Chain Pact Warlocks can pick from other statblocks.