The previous posters nailed the point, but I'd like to mention that Brazilian history as a whole witnessed an improvised "manifest destiny" of sorts, if we consider that the original land claimed by Portugal in respect of the Treaty of Tordesillas was a fraction of the territory that eventually became settled by the Portuguese until the 19th Century.
Check this image, for example - the part in dark green
de jure belonged to the Spanish Empire according to the Papal treaty... and it was occupied and settled by Luso-Brazilian colonists, including the Amazon River region, settled by Jesuitic missions to baptize Indians.
Regarding a Pacific Coast, I find it too hard... until the 20th Century the Brazilian interior (Mato Grosso and Amazonas) was sparsely populated, and any army - Brazilian or not - marching through these places would possibly face problems of supply replenishment, so I find it implausible to launch an invasion of Perú, for example. Beside, the mountainous terrain as we get up the Andes could produce catastrophic results for an invading army, as no soldier from Brazil would have physical preparation for it.
Bolívia might be possible, in theory, as it can be assessed in the south through Mato Grosso, but I find it hard that Brazil succeeded in eating the entire country up. The Hispano-American neighbors will go "full Bolívar" on it
I do believe Paraguay could be annexed, and perhaps the Guyanas and Suriname, depending on which country controls it (the French Guyana was in fact occupied by Luso-Brazilian troops in the 1810s, during the Napoleonic Wars, as Brazil was allied to the UK). Anything else, especially Colombia and Venezuela, I find it too much of a stretch.
After all, for the whole of its "expansionist" History IOTL Brazil was much more interested in the La Plata region than he was in central South America, and had no use for a Pacific enterprise, unlike Argentina, for example.