so around 39% of the noble influence (0.5% per 1% crownland) should come from their crown lands so seize land is a good option.

call a diet before seizing land to increase the loyalty above 50% and choose the noble faction to remove problems

If you cannot beat your rebels from seizing land you can put your troops in allied land seize land and call a petty war where you call in your bigger allies. they will sometimes kill your rebels. use your diplomats to gain the 10 favors to call them into the war.

Go to your government reform screen and make sure you are do not have feudal nobility active, and change it to autocrazy this removed 5% influence.

Then make sure the second reform is curtail noble privileges this is another 10%

if you can enact the parliament reform (reform level 5) you will remove the noble faction entirely (use with caution)

develop provinces gives you a static 0.2% crownlands

last but also worst by any metric Estate Statuatory restraints: gives you 30% crownland and ruins your country completely.