Since ARM11 (ARMv6), cores have been running on Thumb 2 (16-bit instructions) and only jumping into regular 32-bit instructions when necessary. Before that there was the Thumb instruction set which according to [0] was introduced in 1994.
This makes ARM (especially ARMv7 and newer) a mixed setup like x86.
Thumb2 only became standard with ARMv6. There are a few ARMv6 cores which implemented Thumb2 (as opposed to Thumb1), but they aren't in many commonly used products. The ARM1176 for instance as used in the Raspberry Pi is Thumb1 only.
This makes ARM (especially ARMv7 and newer) a mixed setup like x86.
[0] - https://en.wikipedia.org/wiki/ARM_architecture#Thumb