You need consent for all types of sexual activity- including but not limited to kissing, touching, oral sex, intercourse and sexting/sending nudes.
You also need consent every time you engage in sexual activity with someone; even if you’re in a relationship. Just because you or your partner consents to one sexual act does not mean that they consent to other acts.
And, just because someone did something once doesn’t mean they consent to it again.
It’s always best to just ask for consent, for everything and every time.