Of the last 2 noteworthy endorsements that have been made in the presidential primary, (AOC endorsing Bernie, Kerry endorsing Biden) the AOC endorsement is the only one that really held any weight to it. AOC's endorsement of Bernie was a massive statement to the more liberal faction of the Dem party that Bernie may be the true flagbearer of the faction and not Elizabeth Warren, who was polling better than Sanders at this point and is now trailing both Sanders and Biden. Kerry's endorsement meanwhile doesnt hold much weight since anyone who really valued Kerry's opinion likely would have already been a big supporter of Biden due to the extensive similarities between the two.
About a day ago though, Biden secured an endorsement that is very different from the one he received from Kerry, because unlike that one, this endorsement could actually convince voters to support Biden if they didnt do so already. https://www.courthousenews.com/biden-endorsed-by-a-leader-of-house-hispanic-caucus/
Tony Cardenas, A Democratic House Representative from California, is not really a household name by any stretch, especially compared to other House members like Pelosi or even AOC and the Squad. However, Tony Cardenas still holds more influence then about 90% of other House representatives since he is the Chairman of the Congressional Hispanic Caucus, making him the top ranking Latino in the entire Democratic Party.
Up to this point, the Hispanic vote has been pretty up for grabs. Biden does well with older while men (since he is one) and also african american voters (since he was Obama's VP). Sanders does incredibly well with youth voters (As he did in 2016) and Warren has kind of a mosh-pit of support from different groups that Sanders and Biden havent locked down.... The Hispanic vote has not been in anyone's camp up to this point, even though Julian Castro is running for president and was in Obama's cabinet in his 2nd term.
By securing Tony Cardenas's endorsement, Biden has a decently strong opportunity to increase his base of support from Hispanic voters since Cardenas for the most part is the highest ranking Latino politician in the country. If Cardenas doesnt have national influence, his location in California does at least carry regional influence, which is still quite important since California and Nevada are the 3rd and 5th states to vote in the primaries once they begin.