Learn Hardcore Portuguese (Portugal): Se os sapatos estiverem estreitos, a loja pode alargá‑los um pouco. - If the shoes are too tight, the store can stretch them a bit.

Portuguese uses the future subjunctive after se when talking about a possible/unknown future condition. Estiverem is the future subjunctive (3rd person plural of estar).

Estão = present indicative (a present fact or habit).
Estejam = present subjunctive, used after triggers like que, talvez, not typically after se for future conditions.

Could I say Se os sapatos forem estreitos instead of estiverem estreitos?

Yes, but the nuance changes.

Estiverem (from estar) focuses on the state/fit at the time (how they feel on your feet).
Forem (from ser) implies an inherent characteristic (the model runs narrow). For a customer’s current fit, estiverem (or apertados) is more idiomatic.

Is estreitos the best word for “tight,” or would apertados be better?

For shoes, apertados is the most idiomatic way to say “tight.”

Estreitos = narrow (especially width as a characteristic).
Apertados = tight (they press/squeeze your foot).
Justos = close-fitting/snug (not necessarily uncomfortable).

What exactly does alargar mean? Is it the same as largar or esticar?

Alargar = to widen/enlarge (what a shop or cobbler can do to shoes).
Largar = to drop/let go (unrelated).
Esticar = to stretch (lengthen, pull), not the usual verb for widening shoes.

What is the -los in alargá-los?

It’s the unstressed direct-object pronoun os (“them,” referring to os sapatos), attached to the infinitive alargar with a hyphen: alargá-los = “to widen them.” This is standard in European Portuguese when an infinitive takes a clitic.

Why is there an acute accent in alargá-los?

When you attach a clitic to an infinitive (e.g., alargar → alargá‑los), the word’s default stress would shift. The accent is added to keep the original stress on the final syllable of the verb stem: a-lar-GAR → a-lar-GÁ-los.

Could I say A loja pode os alargar instead of pode alargá‑los?

It’s possible but much less natural in European Portuguese. The preferred placement with a modal + infinitive is to attach the clitic to the infinitive: A loja pode alargá‑los.
With a proclisis trigger (e.g., não), you’d say: A loja não os pode alargar.

Why do we need the article os in os sapatos?

Portuguese generally uses definite articles with specific nouns more than English does. Here, os sapatos refers to the specific shoes in question; Se sapatos estiverem… is ungrammatical.

What is the a in a loja—article or preposition?

It’s the feminine singular definite article (“the”): a loja = “the shop.” It’s not the preposition a (“to”). If you meant “in the shop,” you’d use na loja (em + a).

Is the comma after the se-clause required?

Yes. When the subordinate clause comes first, Portuguese uses a comma: Se …, (then) …. If you flip the order, you omit it: A loja pode alargá‑los um pouco se os sapatos estiverem estreitos.

Where does um pouco go? Can I move it?

The default is after the verb phrase: pode alargá‑los um pouco. Other natural options:

pode alargar os sapatos um pouco (if you repeat the noun)
pode alargá‑los só um pouco (adding “only”)
Placing it before the main verb is unusual here.

Is um pouco the most natural expression in Portugal? What about um bocado/um bocadinho?

All are fine in Portugal.

um pouco = a bit (neutral).
um bocado / um bocadinho = very common colloquial alternatives (the latter is a bit more diminutive).

How would I say “The shop can widen them for you”?

Explicit indirect object: A loja pode alargar‑lhe os sapatos um pouco.
Clitic cluster (more compact/written): A loja pode alargá‑lhos um pouco.
Here, lhe = “to/for you” (formal or third person), and ‑lhos = “them for him/her/you.”

Could I use consegue instead of pode?

Yes, with a nuance:

pode = can/is allowed/is able (general possibility or permission).
consegue = manages to/is capable (focuses on ability to achieve it).
Both fit: A loja consegue alargá‑los um pouco emphasizes practical ability.

Any differences in Brazil?

Mainly pronoun placement and choice in speech: in Brazil, colloquial speech often avoids object clitics, so you’ll hear A loja pode alargar os sapatos or even nonstandard pode alargar eles in everyday talk. In European Portuguese, stick with pode alargá‑los or repeat the noun.