My impression, which is admittedly from sources with more or less the same ideological stance towards Trump, is that there are optimistically two:
1) It forced Senate and House Republicans to pin their colours to the mast regarding pro-Trump or pro-democracy, decency, etc. and anti-Civil war, domestic terrorism etc. That many tried to weasel out with the 'it's unconstitutional to impeach an ex-President' excuse I don't think is really holding any weight. Democrat challengers to these positions in 2022 and 2024 will in theory very easily be able to paint their Republican opponent as endorsing the events of January 6th. This will presumably concern moderate Republicans and otherwise undecided voters.
2) It has pushed the Republican party even further into the hands of the extreme right.
There has been a pretty uniform backlash against those decent Republicans who refused to cowtow to the Trump fanatics, and they are being forced out of the party. As above, the more that reasonable and moderate Republicans are replaced by lunatics like Lauren Boebert, the more the typical undecided, moderate voter is likely not to vote for the party.
This might be a bit optimistic, but I think the landslide in 2020 is testament to the fact that, while Trump's base is obviously very steadfast and very vocal, the vast majority of Americans are repelled by him and his ilk.