Depends.
If you're in the normal mode, you have to level up your familiarity with an enemy or something (the thingy you check in one of the status windows), which unlocks tiers of animations during consensual sex (like how you have 5 tiers of animations and 5 levels of familiarity with a mob).
If you're in H-mode, all animation tiers and you can switch to them in the few initial stages of sex (not exactly sure how that works exactly, let's say you have 5 animation stages, if you go to the 2nd stage you can only switch between animation tiers of the same sex type) during casual sex, which technically is an unlockable perk, but H-mode activates all (most?) of those perks anyway.
So in case of one of those all-the-way-through tentacle animation you have sex with a single tentacle, click the anal sex icon in the bottom left of the screen and select tier 4 or so (idk which one it was).
When it comes to DP (and probably gangbang too), when you have sex with a single enemy and either have the relevant perk unlocked or are in H-mode, you get a list of nearby enemies on the right of your screen. Each enemy will have an icon showing what kind of sex they want to perform and this will change which DP (gangbang?) animation they'll play, which afaik you can't change the same way you can do with single enemy sex. You can, however, switch your first enemy to any position to mix with the next enemy's position to influence which group sex animation will be played, then select the second (or third) enemy to have them join.
Personally I don't play the "normal" mode, because the combat is garbo and you're more likely to die from enemies animation cancelling attacks (which still happens with tentacles even in H-mode, if you run into them, you instantly die) than to get raped, which makes obtaining the surrender/entice "skill" pretty damn annoying.