Welcome to the boards, LesVeggies.
It's pretty unlikely anyone's penis is too big for intercourse, be it vaginal or anal or oral sex, for that matter. That said, folks with larger penises may need to pay attention to some things a bit more than those with smaller ones, like:
1) Communicating with your partner to be sure that they are really turned on before trying intercourse, which will usually involve spending plenty of time with other sexual activities that aren't intercourse and that turn them on first.
2) Always using plenty of quality lubricant as you start intercourse, adding throughout.
3) Being gradual as you begin intercourse, only pushing in more as you feel their orifices pulling you in some or yielding to you (everyone should do this, btw, including people using fingers, and it's hard to describe what that feels like, but if you pay attention, it's something where once it happens, you will probably get what I am saying), and only pushing more in when they communicate to you that it feels good.
4) Only having intercourse when your partner really, really wants to do that, not just when they are doing it because it's what you want or they think they have to say yes to.
5) Making whatever adjustments you need to with any given partner and any kind of sex if and when your penis size is an issue for them. All of our bodies are so different, so sex with any given partner always means learning how their body works with ours.
Really, all the things that can cause pain with intercourse for the partner whose orifice is involved can cause pain no matter someone's penis size, so I want to make sure you know that, too.
If you're worried about this with vaginal intercourse in particular, this article may come in handy:
https://www.scarleteen.com/read/sex-sex ... ntercourse I think this one is also a goodie for anyone who wants to have intercourse of any kind with a partner:
https://www.scarleteen.com/read/sex-sex ... ette-entry
Good on you for thinking ahead about how things will feel for your partners! How does all of this land with you? Does it leave you with any extra questions or things you want to talk about?