As
@athousandbands has said, it’s very unlikely - Apple has followed the same pattern as last year and dropped Summer Bands (colours) already for this year in the Spring Release. There have also been no new colours found in the WatchOS.
What is very well possible as the iPhone 13 line is also following the same pattern as last year regarding accessories is, three new Silicone Case colours for summer (that will likely
not be matched across the Watch Band line, also like last year). However, my gut says this is very sadly looking less likely as the event is pretty soon and that Twitter Guy hasn’t leaked any new cases like he normally does these days. If Apple doesn’t drop new cases for Summer, then it would be a first since 2017