Your "what-about-ism" is highly flawed.
There are similarities between how Hillary Clinton and Donald Trump have handled losing a presidential election. Both of them have whined, and cast the results as illegitimate, but there are significant differences as well.
Principally, Clinton didn't already have a foothold in the office, that comes with being the incumbent president. She couldn't use the powers of the presidency at her disposal to overturn the results of her own electoral defeat, as Trump clearly did.
Clinton didn't file over a dozen baseless lawsuits in order to overturn her defeat, and she didn't exert pressure on her fellow party members to help her overturn the election.
Also, in spite of her whining, Hillary Clinton did concede defeat the day after the 2020 Presidential Election. She even attended Trump's inauguration.
Finally, there wasn't a January 6th-style incident after Clinton's defeat. She never called for protest demonstrations either.
In summation, while Trump went to some great lengths to overturn his defeat, Clinton has been all talk.