Can "had worked" substitute for "worked"?

[Kohyoongliat]

My uncle worked as sales manager for 20 years, but now he has his own work.

Can “had worked” substitute for “worked”?

Thanks.

[Torsten]

There is no need for the ‘had worked’ construction:

My uncle worked as a sales manager for 20 years, but now he has his own job.

[Anglophile]

As I agree with Torsten, I can give you another version with the past perfect tense:

My uncle had worked as a sales manager for 20 years before he chose to have his own job.

[Masme]

I agree with Torsten and Anglophile. You don’t need a past perfect construction - past before past. Your uncle worked as a sales manager and now he has his own work. So, that’s the past and the present state of affairs.