Structures I’ve seen in books and never been quite sure how to parse. According to Ciberdúvidas,
Vir + A + Infinitive
Is a periphrastic form of a verb. Wait, wait, hold it right there, what is a periphrastic form? It just means you use extra words to give the verb a slightly different dynamic or even to change the tense. In english it’s things like “You shall go to the ball” or “I do like chips”. It might change the verb’s tense or it might just make it sound more complete and more dynamic. Maybe like in English: How do you come to be in a place like this? It has the sense of ending up somewhere by chance, and it sounds more interesting than “How did you get here?” or “Why are you here?”
There’s an example in the book I’m reading now. Talking about Bolsonaro’s attempts to blame minorities for everything Ricardo Araújo Pereira says “Acredito que a gente ainda venha a descobrir que há inúmeros gays negros e índios na Lava Jato”.
Chegar + A + Infinitive
“Chegar a”, on the other hand is more like “finally managed to…”. It’s stressing the end of the action coming after a long time or a strenuous effort. Searching for an example similar to the one above, I hit on this one which is from a religious website talking how, after a lot of prayer, the believer can finally come to understand the project that God has laid out:
A oração também se torna caminho para o discernimento vocacional, não só porque Jesus mesmo convidou a rogar ao dono da messe, mas porque é somente na escuta de Deus que o crente pode chegar a descobrir o projeto que Deus mesmo traçou: no mistério contemplado, o crente descobre a própria identidade, «escondida com Cristo em Deus»