No. Sperm gets where it needs to go in seconds.Not getting up and peeing right after sex will only increase your chance of getting a UTI.

Scientifically the sperm gets to where it needs to be within seconds, therefore it’s not necessary to leave it in, however I’ve done 1 IUI which unfortunately failed and they made me wait with my butt slightly elevated for 5 minutes after injecting the sperm so I guess it can’t hurt??