On the PSR-E453, the GM1 "Synth Brass 1" sound is voice number 527. The reason you weren't able to find it when browsing through the voices is probably because it's in the "XG Brass" category, not in a synth category. GM1 and other MIDI standards (GM2, GS, XG, etc.) often classify certain classic synth sounds under non-synth categories, depending on the nature of the sound. For instance, FM electric piano sounds will often be in the "Electric Piano" category even though they're DX synth sounds; synth bass sounds will often be in the "Bass" category; synth string sounds will often be in the "Strings" category; synth brass sounds will often be in the "Brass" category; synth vocal sounds will often be in the "Choir" category; etc.
"Synth Brass 1" is GM1 Program Number 63 (or 62 using the internal 0-127 data values), so other voices with Program Number 63 in other banks might be possible alternatives to try out:
Voice 128 - "80s Brass" (Program 63, Bank 0:113)
Voice 129 - "Fat Synth Brass" (a Dual Voice version of Voice 128)
Voice 131 - "Funky Brass" (Program 63, Bank 0:115)
Voice 132 - "Techno Brass" (Program 63, Bank 0:114)
Voice 133 - "Synth Brass" (Program 63, Bank 0:112)
Voice 527 - "Synth Brass 1" (Program 63, Bank 0:0)
Voice 528 - "Quack Brass" (Program 63, Bank 0:12)
Voice 529 - "Resonant Synth Brass" (Program 63, Bank 0:20)
Voice 530 - "Poly Brass" (Program 63, Bank 0:24)
Voice 531 - "Synth Brass 3" (Program 63, Bank 0:27)
Voice 532 - "Jump Brass" (Program 63, Bank 0:32)
Voice 533 - "Analog Velocity Brass 1" (Program 63, Bank 0:45)
Voice 534 - "Analog Brass 1" (Program 63, Bank 0:64)