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 select u.phone, u.email , t.to_address (error from this)
 from user_accounts u 
 where u.id 
 in 
 (select w.user_id 
 from wallets w 
 where w.id 
 in 
 (
 select t.wallet_id 
 from withdraws t 
 where t.to_address 
 in 
 ('1F6o1fZZ7', 'pJDtRRnyhDN')))

I want to get the column to_address from subquery. How can I get it in postgresql?

I try assign 'AS' for subquery but it didn't work

A join returns a result table constructed from data from multiple tables. You can also retrieve the same result table using a sub query. A sub query is simply a SELECT statement within another select statement.

select u.phone, u.email , t.to_address (
 from user_accounts u 
INNER JOIN wallets w ON u.id= w.user_id 
INNER JOIN withdraws t ON t.wallet_id =w.id 
 where t.to_address in ('1F6o1fZZ7', 'pJDtRRnyhDN')

use join with all the table, you dont need any subquery

 select u.phone, u.email , ww.to_address 
 from user_accounts u left join wallets w on u.id=w.user_id
 left jon withdraws ww on w.id=ww.wallet_id
where ww.to_address in ('1F6o1fZZ7', 'pJDtRRnyhDN')

You can not access t.address because that column inside in condition.
I used left join but it seems it will be inner join type because you used filter in ('1F6o1fZZ7', 'pJDtRRnyhDN') though after applying where condition it also behave like inner join

You cannot achieve what you're trying using subquery. When you want records from different tables and they have a unique column in common that connects them then You should do it using a JOIN.

Sometimes (Not all cases) IN can cause performance problems, so you should consider knowing more about different types of JOINS(https://www.w3schools.com/sql/sql_join.asp)

Check the link for comparison:
Inner join versus doing a where in clause

About the Query:

SELECT
 u.phone, u.email , t.to_address (error from this)
FROM
 user_accounts u 
 INNER JOIN wallets w ON u.id = w.id
 INNER JOIN withdraws t ON t.wallet_id = w.id
WHERE
 t.to_address IN ('1F6o1fZZ7', 'pJDtRRnyhDN')