Learn Hardcore French: Au moins, tout le monde a le temps de s’asseoir.

Because tout le monde is grammatically singular (it means “everyone” as a single group), so it takes a 3rd‑person singular verb: tout le monde a, not tout le monde ont.
Follow‑ups can switch to the plural pronoun if you then talk about the people as individuals: Tout le monde a le temps. Ils peuvent s’asseoir.

Why is it tout le monde and not tous le monde?

Use tout with a singular noun and tous with a plural noun.

Singular: tout le monde (everyone)
Plural: tous les gens (all the people)
So you say tout le monde, not tous le monde.

What is the le in a le temps doing? Is it a pronoun?

Here le is the definite article (“the”), not a pronoun. Avoir le temps (de + infinitive) is a fixed expression meaning “to have time (to do something).” It literally says “has the time.”

Why is it le temps de + infinitive and not something with pour or à?

The idiomatic pattern is avoir le temps de + infinitif:

Tout le monde a le temps de s’asseoir.
You can also say avoir du temps pour + infinitif, but that slightly changes the nuance (see next Q&A). Le temps à is not used here.

Can I say Tout le monde a du temps pour s’asseoir instead?

You can, and it’s understandable, but it’s less idiomatic here.

Avoir le temps de + inf. = there is enough time to do it (focus on sufficiency).
Avoir du temps pour + inf. = one has some time for it (focus on available time in general).
In your sentence, the set phrase avoir le temps de is the most natural.

Why is it de s’asseoir and not just de asseoir or se asseoir?

With an infinitive, the reflexive pronoun attaches to the infinitive: se asseoir → elides to s’asseoir before the vowel.

Correct: a le temps de s’asseoir
Incorrect: a le temps de asseoir, a le temps se asseoir

Why the reflexive verb s’asseoir instead of asseoir?

S’asseoir means “to sit down” (the subject sits themselves). Asseoir is the non‑reflexive verb meaning “to seat” someone else: asseoir un enfant (to seat a child). In your sentence, people are sitting down themselves, hence reflexive.

How do you conjugate s’asseoir? I’ve seen different forms.

There are two accepted present‑tense paradigms; both are correct:

Set 1 (assey‑): je m’assieds, tu t’assieds, il s’assied, nous nous asseyons, vous vous asseyez, ils s’asseyent
Set 2 (assoy‑): je m’assois, tu t’assois, il s’assoit, nous nous assoyons, vous vous assoyez, ils s’assoient

Other handy forms:

Past participle: assis/assise (je me suis assis/assise)
Imperative: Asseyez‑vous !

Is the spelling s’assoir (without the first e) acceptable?

Yes. Since the 1990 spelling reforms, (s’)assoir is an accepted variant of (s’)asseoir. Both are correct; (s’)asseoir remains more common in careful writing.

Can au moins go somewhere else in the sentence?

Yes, but word order changes the scope:

Au moins, tout le monde a le temps de s’asseoir. “At least, everyone has time to sit down” (consolation about the whole statement).
Tout le monde a au moins le temps de s’asseoir. “Everyone has at least the time to sit down” (minimum amount of time).
Tout le monde a le temps de s’asseoir, au moins. Same meaning as the first, with a tail comment feel.

What’s the difference between au moins, du moins, and à moins que?

au moins = at least (minimum/quantity or consolation): Au moins, il est venu.
du moins = at least, at any rate (hedging/limitation of what you’re asserting): Il viendra, du moins je l’espère.
à moins que
- subjunctive = unless: On partira, à moins qu’il ne pleuve.

Is the comma after Au moins necessary?

It’s optional but recommended. Au moins acts like a sentence adverb; the comma helps show it comments on the whole clause: Au moins, …

Any quick pronunciation tips for this sentence?

Au = [o]; moins = [mwɛ̃] (final s silent).
Tout in tout le monde is [tu] (final t silent).
Monde = [mɔ̃d] (the d is pronounced). So monde a sounds like [mɔ̃da].
Temps = [tɑ̃] (final ps silent).
De s’asseoir = [də saswaʁ].
Putting it together smoothly: [o mwɛ̃, tu lə mɔ̃d a lə tɑ̃ də saswaʁ].

Could I use something other than tout le monde, like tous, chacun, or les gens?

Yes, with agreement changes:

Tous ont le temps de s’asseoir. (plural verb)
Chacun a le temps de s’asseoir. (emphasizes each individual)
Les gens ont le temps de s’asseoir. (more generic “people”)

How would I negate this structure?

Wrap ne … pas around the conjugated verb, leave the infinitive part as is:

Tout le monde n’a pas le temps de s’asseoir. = Not everyone has time to sit down.
Personne n’a le temps de s’asseoir. = No one has time to sit down. (Using personne for a stronger negative.)

Why temps here and not heure?

Temps is “time” in general. Heure is an hour or clock time. You say avoir le temps de + inf. (to have time to do something), not avoir l’heure de + inf.