Aside from toys made to stimulate specific parts, sex toy companies often make dildos that are much bigger than the average penis. Why this is is not very well-studied, but it could be for several reasons. One is that someone with a vagina would have to angle the toy to use it, such that they can’t get the entire toy inside themselves, so extra length is needed to get the desired length in. Another is that sex toys are to simulate sex that is an unrealistic fantasy for many users.
Whatever the reason, if you have a penis, don’t be intimidated if your partner uses a dildo that’s bigger than you. It’s typically not because that is the size they actually desire in a partner. After all, if someone’s penis is actually the size of many dildos, it would be painful to have PIV and anal sex with a lot of partners. Instead, ask your partner if they’d like for you to incorporate the toy into the sex you two have. It may end up being an enjoyable experience for both of you.
An add on to this is that dildos are rarely the end all be all of sex toys. They’re often a gateway to sex toys because it has a close and comfortable similarity to sexual experiences so its likely the first thing anyone buys, but the options are as diverse as the ways people can get off. The vast majority of them can be used in conjunction with actual sex and heighten the experience for everyone involved. Think of it like painting, you can do a whole painting with a single standard brush, but there are thousands of brushes with specific purposes and they each bring something new to the work.
That’s a good point. I focused on dildos because they’re often a source of insecurity, but all the other toy types do things that human anatomy either can’t or needs to work really hard to do.