If you turn 62 before January 2, 2016, and:

• You are eligible for benefits both as a retired worker and as a spouse (or divorced spouse) in the first month you want your benefits to begin and
• You are not yet full retirement age, you must apply for both benefits (known as deemed filing). You will receive the higher of the two benefits.

If you turn 62 on or after January 2, 2016, and:

• You are eligible for benefits both as a retired worker and as a spouse (or divorced spouse) in the first month you want your benefits to begin, then:
• Deemed filing applies at age 62 and extends to full retirement age and beyond. In addition, deemed filing may occur in any month after becoming entitled to retirement benefits.

Deemed filing means that when you file for either your retirement or your spouse’s benefit, you are required or “deemed” to file for the other benefit as well. The Bipartisan Budget Act extends deemed filing rules to apply at full retirement age and beyond.

The way you phrased the question is complicated.  The spousal benefit is 50% of the other spouse's benefit.

For a spouse who turned 62 before 2016:

If they applied for a benefit on their own record, they could re-apply at full retirement age for their spouse's benefit, but it would only make sense to do that if 50% of the spouse's benefit was more than 100% of their own benefit.

For a spouse who turned 62 in 2016 or after, their application was automatically deemed to be for both programs, and they should automatically be receiving 100% of their benefit or 50% of their spouse, whichever is larger, but not both.