how override New Button and Edit Button with LWC for one particular record type

If you are using a custom object, consider using Dynamic Forms which should allow you to provide much finer control on what the user can and cannot see based on visibility rules. It doesn't enable/disable, but rather hide/show, of course.

As to actions, consider using Dynamic Actions which again allow you to have finer control, including making actions available or not based on rules that use record details.

In standard detail page, dynamically disable the fields can be done only on dependent picklsit, i.e showing different values for picklist in dependent based on master picklist.

Another thing that can restrict user from entering values to a field dynamically using validation rule or trigger.

If you are going for overriding the action, you can not do it based on record types. You need to handle the record types within your components directly.