The only real problem with trimming is that it is the way of women to beautify themselves, but since it is the minhag hamidina nowadays for men to remove certain parts of hair (ie.beard, eyebrows etch…) it should be allowed to cut or trim those parts of hair.
Thank you I really appreciate it.
The main issue with trimming a beard is not lo tilbash, (except according to the Tzemach Tzedek, which is not the minhag haolam) because (B”H) women don’t have beards (See Igros Moshe Y:D 2- 61, Sridei Aish 2 pg. 276), and as you mentioned because in our society it is the minhag even for Jewish men to shave their beards. The issue is more of lo takif, that a man is not allowed to shave his beard in a way that is considered destroying the hairs, such as with a razor. If the blade doesn’t go up against the skin, but leaves some hair, such as with a trimmer, it would be permitted. Regarding a trimming his eyebrows, the poskim say that under normal circumstances that it is included in Lo Tilbash. See sources.
Chayei Halevi 3-63, Nishmas Avrohom 2 pg. 140 in the name of R’ S/ Z/ Auerbach zt”l, Ohel Yackov- Lo Tilbash Y:D 182-11, Tznif MIlucha pg. 200 in the name of R’ C. Kanievsky shlit”a,