That was from
Still miles apart: Americans and the state of U.S. democracy half a year into the Biden presidency | Bright Line Watch
For much of what that page discussed, Democrats, Republicans, and political-science experts were polled on a variety of issues.
The section "Constitutional hardball" had polls on 12 issues, and in only one issue did all three groups agree: rejection of gerrymandering. They only weakly differed, in order R < D < E (experts a bit more than Democrats, in turn a bit more than Republicans).
There were some policies where the E's were between the D's and the R's:
R < E < D: impeach president because unfit
D < E < R: refuse to increase borrowing limit, routine minority filibusters
R < E ~ D (E a bit less than D): increase court size (presumably the Supreme Court)
In all of them, the E's were closer to the D's than to the R's.
There were several policies where the E's were on the same side as the D's but significantly farther:
R < D < E: DC and Puerto Rico statehood, Senate majority abolishes filibuster
E < D < R: not consider Supreme Court nominee, policies that limit voting, local officials refuse to certify, Congress refuses to certify, state legislature picks electors against popular vote
There were none where the E's were on the same side as the R's but significantly farther.
I think that this shows that the Republican Party has become more extreme than the Democratic Party.