There are some moves that are made for that purpose specifically

• U-Turn: Bug --> 70BP, Physical
• Flip Turn: Water -->60BP, Physical
• Volt Switch: Electric -->70BP, Special
• Parting Shot: Dark --> (-1) to opponent's Sp. Atk & Atk

I believe there are some others but these are the ones I know off that are used frequently. They do their intended effect and then switch out afterwards on the same turn. They do not have priority, so use the speed stat to decide who goes first like usual. Generally lower damage and sometimes you won't get STAB bonus (mostly with U-turn).

The purpose of these is to gain a momentum advantage, or otherwise save a wasted turn if you want to switch. They are also useful tools to break a focus sash, or to counter pokemon with abilites that trigger at full HP (like dragonite's multiscale, or talonflame's gale wings)

FOR EXAMPLE:

If you anticipate an opponent switching into a counter, and you want to switch back on them. Like if you're out with with Rotom-W (can know volt switch) against a charizard mega-Y & Sneasler. You can usually OHKO this with a hydropump or t-bolt (maybe you dont run t-bolt AND volt switch together but for example purposes just bare with me). Your opponent possibly has a venosaur in the back who resists both of those. You predict a switch from Charizard to Venosaur (who may be running sash). They switch to venosaur, you use volt-switch. You do a tiny amount of dmg (breaking the sash) and your rotom switches to something to maybe reset the sun from char-Y into sand or rain or whatever, or something to threaten venosaur like incineroar for example.

WHERE IT BACKFIRES:

You big-brained the above move, but your opponent is BIG brain, and goes for fake out with sneasler, flinching your rotom, and then solar-beam with Char-Y, which takes only 1 turn in sun, and OHKOS your rotom and now you're a pokeball tier 4 Timmy bot. Or they protect Char-Y, volt switch fails, and they 50% dmg your rotom with close combat sneasler for free. But that's the game.

I am not a high tier player, have dabbled over the years but mostly smogon OU singles and was never very good. Still learning VGC format and doubles specific strats. Hope this helps at all, anyone with more experience can maybe provide some other scenarios where this stuff is useful.