The only indication we have of any special favour Aragorn may have had from the Valar is his lifespan, the longest in a very long time and a throwback to the ancient Númenórean Kings (emphasis mine):
It was the pride and wonder of the Northern Line that, though their power departed and their people dwindled, through all the many generations the succession was unbroken from father to son. Also, though the length of the lives of the Dúnedain grew ever less in Middle-earth, after the ending of their kings the waning was swifter in Gondor; and many of the Chieftains of the North still lived to twice the age of Men, and far beyond the days of even the oldest amongst us. Aragorn indeed lived to be two hundred and ten years old, longer than any of his line since King Arvegil; but in Aragorn Elessar the dignity of the kings of old was renewed.
Return of the King Appendix A "Annals of the Kings and Rulers" I "The Númenórean Kings" (iii) Eriador, Arnor, and the Heirs of Isildur
However, whether or not this "special favour" kicks in before or after his ascent to the throne is unknown. During the course of Aragorn's life before he becomes King Elessar, we have no indication that the Valar had any special interest in him.