Pa... yes, normally. Just becareful if growing from seed, do the pinching after the first set of true leaves. Can I ask, what 's ya wanna pinch? Also when your plants begin blooming make sure to deadhead, this can (depending on the plant) give you 2 extra branches to get blooms from the whole season.
I am growing annual baby's breath (started from seed and now have 2 pairs true leaves) that I would like to see grow into less spindly plants. I grew them 2 years ago and they were tall and spindly and seemed to flop all over the place. I had grown calendula too, and they were the same way. Can I pinch? :>)
I dont pinch out till there has been a few inches of growth as if done too early you might find the plant just dies from shock and has not enough energy to regrow side shoots if done at true leaf stage, I have friends who dont pinch out till the plants are ready / hardy enough to be set out into the planting area, as they set the plants in there planting hole they pinch each plant out, add a handfull of general multi purpose feed or fish/blood/bonemeal to the soil when prepared for planting and this will feed the plants for the best part of the summer, hope this help, good luck, WeeNel.